"but I assume it means that any derivatives I make from the art there has to be released under that license and must credit the original author, right? I'm perfectly fine with that."
This is correct.
"But what about making a game that uses such an asset? Does that mean that the source code has to be released under that license, too?"
Certainly not, because even if you had to release the game as CC BY-SA, that licence doesn't say anything about source code.
What is unclear though is whether CC BY-SA does apply to the entire game - if it did, then it would mean people would be free to distribute your game under that licence.
Is this a commercial project, or just for free/fun? If the former, these are questions to ask a lawyer. If the latter, why not release the source anyway?
Or if you mean you're happy to release the source, but are asking whether it has to be released under CC BY-SA. In practice, plenty of people release source under licences like GPL or BSD, even if they use CC BY-SA art. It is an unfortunate problem with CC BY-SA that if it really applied to the entire game, it would mean the source would have to be CC BY-SA too.
If you're going to be drawing on top of it, it's still going to be a derivative work, so not okay.
At first I thought they were actually using the LPC sprites ( http://lpc.opengameart.org/static/lpc-style-guide/assets.html ), though it does seem slightly different (e.g., different height proportions). But then having said that, if you just want a base template, how about using the LPC ones instead?
Recent versions have added a 3rd quest, and a new gameplay mode with a random dungeon, among various other improvements.
I've tested it on my Samsung Galaxy Nexus and the Android emulator, so please let me know if anyone experiences problems. It requires Android 2.3.3 or better, and a resolution of 800x480 or higher. This also requires installing the app Ministro, which you should be prompted to do when you first run Erebus (if it's not already installed). Ministro manages the required Qt libraries on Android. The libraries can take up to around 25MB, so it may be best to download over a Wifi connection.
I'd say that the problem of "Light objects neutrally" is why providing "different rotations of the same image" is a useful thing - because once you have lighting/shadows, creating the different orientations isn't as simple as just doing a rotation. (This doesn't apply to the spaceship example, which does seem to be a simple rotation, but I think it's a point worth mentioning in general.)
It's true that one can simplify things if objects are lit from above, but I think isometric games do look better with a shadow cast to the side.
If I was writing an Asteroids game, I would rotate at run-time as "orient in any direction" is a key part of a game - but for cases where the directions are more limited (e.g., 4 or 8), providing multiple images can give better quality.
On APIs, in an ideal world APIs like SDL would all be GPU optimised, but they're not, and rightly or wrongly, there are people with games and engines built on SDL (perhaps because it's the APIs they know and it works, or there's a big codebase that would need porting).
Plus I don't see why this is a problem for you anyway - if you only need one image because you can rotate at runtime, then simply take one image. At worst, the artist wasted his time, I don't see how it slows you down :)
I prefer to use an alpha channel rather than colour keys these days, and it's easier to work with (e.g., one can scale the image with anti-aliasing - if you do that to an image with a colour key, you'll get a "fringe" effect where the colour key is blended with adjacent pixels, and is no longer invisible as it's a slightly different colour). But again, I don't see it as a problem, it's easy enough to convert (e.g., the Grim Color Reaper plugin for Paint.NET). If you think it's easy to switch to a new API, then it should be easy for you to convert the image.
If we want to consider modern techniques, why bother with 2D images at all? Just render the 3D object directly, then you can decide on things like the lighting yourself. What are the advantages of using the 2D images?
In paper RPGs, races like goblins/orcs have often been inherently evil - and in that sense, killing them is no more unethical than killing demons.
Another way of looking at it I think is that the races are essentially at war - or alternatively, it is a matter of survival.
I thought it interesting how in Morrowind (and presumably the other Elder Scrolls games), creatures like Orcs were friendly, and the enemies you encountered were either other humans or undead/demonic/magical. Though I don't think it avoids the issue of killing (indeed, in that game, you are killing other humans), just the races behave differently.
In theory, I like the idea of an RPG that has a focus on things other than killing, and isn't simply about killing room after room full of monsters. However I think writing such a thing is far from easy - you need a far larger amount of ideas, just for a small amount of gametime. Plus it doesn't change that killing enemies is still a core part of most RPGs - it's like saying it should be possible to complete a shoot 'em up without killing things :)
One advantage of having XP awarded on smaller things like killing creatures, and having them respawn, is it makes it easier to balance the gameplay - if it's too hard for a player, they can always get stronger by killing a few more creatures.
With paper RPGs where you have a human GM, it's easier to deal out the XP at the end of a quest (or major part), because a human can better use their judgement to decide how much a person deserves or needs to balance the game.
I don't know how similar to Fallout that is, though I note what you've described sounds like most of the RPG systems out there... I don't know if there's ever been a court case covering RPG rule systems(?) The cases I know apply to complete remakes, which includes issues such as trademarks and copyrighted art (e.g., I think there was a case involving the Talisman game, but can't find a link atm).
As for patents - as I say, remember that could apply to every aspect of a game, as well as every algorithm you write. Sadly the only 100% way to be sure is to get a lawyer, but we have to be pragmatic, in practice most individuals, hobbyists and Open Source programmers aren't going to be able to do this, and it seems to be a better tactic simply to steer clear of known patents. I don't think there's anything special about "RPG rules".
And yes I hope we haven't scared off RainHippie! Really my point is that one shouldn't worry too much about things like patents when you're learning to program.
True, I'd agree that if you're going to copy something 100%, it's perhaps better to use one that's properly released under a licence that lets you do what you want to do with it. I don't think I'd worry about the words if they're perfectly good words to describe something (e.g., "Fighting Prowess"). More specific made-up words may be best to avoid, and this also crosses over into Trademarks (e.g., everyone avoids using the word "Hobbit" because it's trademarked, even though loads of people and companies have happily ripped off large chunks of Tolkien's world, including "halflings").
Rules could be patented in some countries. There is indeed the problem that one can't know if something is patentable without doing an extensive patent search - unfortunately this applies to everything in software development, from any kind of game mechanics, to algorithms. And it applies whether you copy one thing entirely, draw inspiration from various games, or even independently recreate it yourself. In practice, I think that means that one either (a) never releases code at all, (b) hires a lawyer to do patent searches, or (c) not care so much, and avoid things which are known to be patented (e.g., Carmack's Reverse shadowing algorithm, or mp3 playback) (or (d), live in a country where pure software patents aren't enforcable).
"It seems pretty clear to me that implementing a ruleset in source code is a derivative work and therefore would trigger the "share alike" provisions of a copyleft license. I don't see how one can argue that it's not a derivative work."
In which case, I feel it would be inconvenient in many cases - as I say, many of the licences for documents/rules/art aren't suitable for software (so CC BY-SA would mean the game source/binary has to be CC BY-SA). But still, I don't think that matters, as the issue is the expression of the rules, not implementing the rules themselves in source.
"Non-commercial licenses are only incompatible with copyleft licenses. You can release something derived from a permissively licensed work as full-blown closed source if you wanted. If you mean that you're game would not be truly open source if you had non-commercial provisions in the license, I agree."
Yes I agree - it's possible to mix Free software with non-Free art/rules. But it's worth considering the consequences of non-commercial restrictions (e.g., http://freedomdefined.org/Licenses/NC ), just as with non-commercially licensed art. Thanks for the links anyway btw - I just wanted to point out for people to beware that not all of the categories are Free licences.
Yes, I don't think anyone is saying you should open your source.
Having said that though - noting you say "but when Ive finished and cleaned the code maybe I will open it up", I would say it is a good thing to release source if you've no reason to keep it closed. I know that one fear is that people will unhelpfully criticise the code - this used to be one of my worries - but I've never had anyone do this. It's a good thing to clean up source, but that's true whether it's open or closed, for your own benefit :)
Some of the benefits of open source are: allowing other people to more easily spot problems (if the people reporting bugs are also programmers); other people might port to other platforms; more interest from sites that cover Open Source games; being able to use various free hosting sites available for Open Source (e.g., Sourceforge, Google Code); easy backup for your source (the online source or repository is your online backup).
@cemkalyoncu: "Open source software is alot different from libre software in terms that the latter allow distribution and modification. Where as open source software can be restricted as you have stated. "
I don't think that's true. Both Free Software and Open Source cover more liberal licences like BSD - I think you're describing the difference between copyleft and non-copyleft. There is a difference in philosophy between Free Software and Open Source, though it's actually the Free Software Foundation that puts more emphasis on copyleft licences like the GPL (which they wrote) to preserve freedom for users; the Free Software movement also seems more focused on the ethics of software. See http://stackoverflow.com/questions/276957/the-difference-between-free-so... for some discussion and links. In practice, the list of licences they each count as Free/Open seem pretty similar.
@mainsworthy: "open source isnt free, you may have to buy a licence even though its open source"
This would apply say, if it was a copyleft licence like GPL, but you wanted to distribute under different terms - in some cases, you can buy a licence with those rights (e.g., Qt is available under the Free LGPL, as well as a commercial licence). In other cases, you can't at all. Is that what you were thinking of?
"where does it end though, The game and source code I could give away free, but the compiler costs money has to be bought! so free software also limits your freedom of compilers, and graphics software!"
The issue is freedom rather than cost.
Yes, it's true that one can produce an Open Source program that still requires a closed source compiler to build, or a closed source operating system to run. I think there are various answers to this:
* The Free Software community have provided a Free set of tools, including graphics software, compilers, and even a complete operating system. The FSF might prefer that people write Free Software purely with Free tools, for Free platforms, but I guess there's a pragmatic view that Free Software on closed source platforms is still better than closed source software on closed source platforms.
* For people who release as Open Source, either for the benefits I list above, or because they believe it's right, that doesn't necessarily mean they believe every software must be Open Source (this is closer to my point of view - I develop on Windows and often use Visual Studio - porting to Linux is more because it gets more interest, than out of ethical considerations). Still, there is the practical point of view that you'll probably get more interest if people can compile and work on the problem with free (as in no cost) tools. But then, even closed source programs like Visual Studio Express and Paint.NET are no cost :) (And these days, the compiler differences between VC and GCC are fairly small.) I don't know what language you used - is it something that people would have to pay to get a compiler for?
It's good to look at other RPG rules, e.g. for inspiration, but not to hard to write your own system. (Personally I like to not overcomplicate the rules - it's tempting come up with complex rules, but that's often overkill if the game doesn't make use of those rules.)
I'd only worry about that if say you wanted copy the instructions themselves, rather than copying game rules. (IANAL!)
A licence that tried to say that the game as a whole would have to be distributed under the same licence as used for the rules would be pretty inconvenient in most cases, as most of the licences for documents or game rules aren't going to be suitable for software. (This is similar to the debate as to whether CC BY-SA for art would also affect the game software.)
And even if the OP isn't trying to make money, a non-commercial restriction on the game would make it incompatible with Open Source licences. (Again, the same thing applies to art - and is why non-commercial licences aren't allowed on this site.)
There's free as in no cost, and free as in freedom - not taking a point of view, but it's important to note that these are two distinct meanings of the same word. Furthermore, "Free Software" (as a term in itself - note the capitals - rather than the literal meaning of software that's free) often refers to that as defined by the FSF (similar to "Open Source" being that defined by the OSI).
I agree with bart's first reply. There are plenty of Free art licences that allow usage with non-Free software (indeed, possibly most of them), so there's not really a problem. But there might be the practical point that some people on this site may be more willing to create art for Free / Open Source games.
"but I assume it means that any derivatives I make from the art there has to be released under that license and must credit the original author, right? I'm perfectly fine with that."
This is correct.
"But what about making a game that uses such an asset? Does that mean that the source code has to be released under that license, too?"
Certainly not, because even if you had to release the game as CC BY-SA, that licence doesn't say anything about source code.
What is unclear though is whether CC BY-SA does apply to the entire game - if it did, then it would mean people would be free to distribute your game under that licence.
Is this a commercial project, or just for free/fun? If the former, these are questions to ask a lawyer. If the latter, why not release the source anyway?
Or if you mean you're happy to release the source, but are asking whether it has to be released under CC BY-SA. In practice, plenty of people release source under licences like GPL or BSD, even if they use CC BY-SA art. It is an unfortunate problem with CC BY-SA that if it really applied to the entire game, it would mean the source would have to be CC BY-SA too.
If you're going to be drawing on top of it, it's still going to be a derivative work, so not okay.
At first I thought they were actually using the LPC sprites ( http://lpc.opengameart.org/static/lpc-style-guide/assets.html ), though it does seem slightly different (e.g., different height proportions). But then having said that, if you just want a base template, how about using the LPC ones instead?
Erebus is now available for Android phones/tablets on Google Play! https://play.google.com/store/apps/details?id=net.sourceforge.erebusrpg
Recent versions have added a 3rd quest, and a new gameplay mode with a random dungeon, among various other improvements.
I've tested it on my Samsung Galaxy Nexus and the Android emulator, so please let me know if anyone experiences problems. It requires Android 2.3.3 or better, and a resolution of 800x480 or higher. This also requires installing the app Ministro, which you should be prompted to do when you first run Erebus (if it's not already installed). Ministro manages the required Qt libraries on Android. The libraries can take up to around 25MB, so it may be best to download over a Wifi connection.
I'd say that the problem of "Light objects neutrally" is why providing "different rotations of the same image" is a useful thing - because once you have lighting/shadows, creating the different orientations isn't as simple as just doing a rotation. (This doesn't apply to the spaceship example, which does seem to be a simple rotation, but I think it's a point worth mentioning in general.)
It's true that one can simplify things if objects are lit from above, but I think isometric games do look better with a shadow cast to the side.
If I was writing an Asteroids game, I would rotate at run-time as "orient in any direction" is a key part of a game - but for cases where the directions are more limited (e.g., 4 or 8), providing multiple images can give better quality.
On APIs, in an ideal world APIs like SDL would all be GPU optimised, but they're not, and rightly or wrongly, there are people with games and engines built on SDL (perhaps because it's the APIs they know and it works, or there's a big codebase that would need porting).
Plus I don't see why this is a problem for you anyway - if you only need one image because you can rotate at runtime, then simply take one image. At worst, the artist wasted his time, I don't see how it slows you down :)
I prefer to use an alpha channel rather than colour keys these days, and it's easier to work with (e.g., one can scale the image with anti-aliasing - if you do that to an image with a colour key, you'll get a "fringe" effect where the colour key is blended with adjacent pixels, and is no longer invisible as it's a slightly different colour). But again, I don't see it as a problem, it's easy enough to convert (e.g., the Grim Color Reaper plugin for Paint.NET). If you think it's easy to switch to a new API, then it should be easy for you to convert the image.
If we want to consider modern techniques, why bother with 2D images at all? Just render the 3D object directly, then you can decide on things like the lighting yourself. What are the advantages of using the 2D images?
In paper RPGs, races like goblins/orcs have often been inherently evil - and in that sense, killing them is no more unethical than killing demons.
Another way of looking at it I think is that the races are essentially at war - or alternatively, it is a matter of survival.
I thought it interesting how in Morrowind (and presumably the other Elder Scrolls games), creatures like Orcs were friendly, and the enemies you encountered were either other humans or undead/demonic/magical. Though I don't think it avoids the issue of killing (indeed, in that game, you are killing other humans), just the races behave differently.
In theory, I like the idea of an RPG that has a focus on things other than killing, and isn't simply about killing room after room full of monsters. However I think writing such a thing is far from easy - you need a far larger amount of ideas, just for a small amount of gametime. Plus it doesn't change that killing enemies is still a core part of most RPGs - it's like saying it should be possible to complete a shoot 'em up without killing things :)
One advantage of having XP awarded on smaller things like killing creatures, and having them respawn, is it makes it easier to balance the gameplay - if it's too hard for a player, they can always get stronger by killing a few more creatures.
With paper RPGs where you have a human GM, it's easier to deal out the XP at the end of a quest (or major part), because a human can better use their judgement to decide how much a person deserves or needs to balance the game.
I don't know how similar to Fallout that is, though I note what you've described sounds like most of the RPG systems out there... I don't know if there's ever been a court case covering RPG rule systems(?) The cases I know apply to complete remakes, which includes issues such as trademarks and copyrighted art (e.g., I think there was a case involving the Talisman game, but can't find a link atm).
As for patents - as I say, remember that could apply to every aspect of a game, as well as every algorithm you write. Sadly the only 100% way to be sure is to get a lawyer, but we have to be pragmatic, in practice most individuals, hobbyists and Open Source programmers aren't going to be able to do this, and it seems to be a better tactic simply to steer clear of known patents. I don't think there's anything special about "RPG rules".
And yes I hope we haven't scared off RainHippie! Really my point is that one shouldn't worry too much about things like patents when you're learning to program.
True, I'd agree that if you're going to copy something 100%, it's perhaps better to use one that's properly released under a licence that lets you do what you want to do with it. I don't think I'd worry about the words if they're perfectly good words to describe something (e.g., "Fighting Prowess"). More specific made-up words may be best to avoid, and this also crosses over into Trademarks (e.g., everyone avoids using the word "Hobbit" because it's trademarked, even though loads of people and companies have happily ripped off large chunks of Tolkien's world, including "halflings").
Rules could be patented in some countries. There is indeed the problem that one can't know if something is patentable without doing an extensive patent search - unfortunately this applies to everything in software development, from any kind of game mechanics, to algorithms. And it applies whether you copy one thing entirely, draw inspiration from various games, or even independently recreate it yourself. In practice, I think that means that one either (a) never releases code at all, (b) hires a lawyer to do patent searches, or (c) not care so much, and avoid things which are known to be patented (e.g., Carmack's Reverse shadowing algorithm, or mp3 playback) (or (d), live in a country where pure software patents aren't enforcable).
"It seems pretty clear to me that implementing a ruleset in source code is a derivative work and therefore would trigger the "share alike" provisions of a copyleft license. I don't see how one can argue that it's not a derivative work."
In which case, I feel it would be inconvenient in many cases - as I say, many of the licences for documents/rules/art aren't suitable for software (so CC BY-SA would mean the game source/binary has to be CC BY-SA). But still, I don't think that matters, as the issue is the expression of the rules, not implementing the rules themselves in source.
"Non-commercial licenses are only incompatible with copyleft licenses. You can release something derived from a permissively licensed work as full-blown closed source if you wanted. If you mean that you're game would not be truly open source if you had non-commercial provisions in the license, I agree."
Yes I agree - it's possible to mix Free software with non-Free art/rules. But it's worth considering the consequences of non-commercial restrictions (e.g., http://freedomdefined.org/Licenses/NC ), just as with non-commercially licensed art. Thanks for the links anyway btw - I just wanted to point out for people to beware that not all of the categories are Free licences.
Yes, I don't think anyone is saying you should open your source.
Having said that though - noting you say "but when Ive finished and cleaned the code maybe I will open it up", I would say it is a good thing to release source if you've no reason to keep it closed. I know that one fear is that people will unhelpfully criticise the code - this used to be one of my worries - but I've never had anyone do this. It's a good thing to clean up source, but that's true whether it's open or closed, for your own benefit :)
Some of the benefits of open source are: allowing other people to more easily spot problems (if the people reporting bugs are also programmers); other people might port to other platforms; more interest from sites that cover Open Source games; being able to use various free hosting sites available for Open Source (e.g., Sourceforge, Google Code); easy backup for your source (the online source or repository is your online backup).
@cemkalyoncu: "Open source software is alot different from libre software in terms that the latter allow distribution and modification. Where as open source software can be restricted as you have stated. "
I don't think that's true. Both Free Software and Open Source cover more liberal licences like BSD - I think you're describing the difference between copyleft and non-copyleft. There is a difference in philosophy between Free Software and Open Source, though it's actually the Free Software Foundation that puts more emphasis on copyleft licences like the GPL (which they wrote) to preserve freedom for users; the Free Software movement also seems more focused on the ethics of software. See http://stackoverflow.com/questions/276957/the-difference-between-free-so... for some discussion and links. In practice, the list of licences they each count as Free/Open seem pretty similar.
@mainsworthy: "open source isnt free, you may have to buy a licence even though its open source"
This would apply say, if it was a copyleft licence like GPL, but you wanted to distribute under different terms - in some cases, you can buy a licence with those rights (e.g., Qt is available under the Free LGPL, as well as a commercial licence). In other cases, you can't at all. Is that what you were thinking of?
"where does it end though, The game and source code I could give away free, but the compiler costs money has to be bought! so free software also limits your freedom of compilers, and graphics software!"
The issue is freedom rather than cost.
Yes, it's true that one can produce an Open Source program that still requires a closed source compiler to build, or a closed source operating system to run. I think there are various answers to this:
* The Free Software community have provided a Free set of tools, including graphics software, compilers, and even a complete operating system. The FSF might prefer that people write Free Software purely with Free tools, for Free platforms, but I guess there's a pragmatic view that Free Software on closed source platforms is still better than closed source software on closed source platforms.
* For people who release as Open Source, either for the benefits I list above, or because they believe it's right, that doesn't necessarily mean they believe every software must be Open Source (this is closer to my point of view - I develop on Windows and often use Visual Studio - porting to Linux is more because it gets more interest, than out of ethical considerations). Still, there is the practical point of view that you'll probably get more interest if people can compile and work on the problem with free (as in no cost) tools. But then, even closed source programs like Visual Studio Express and Paint.NET are no cost :) (And these days, the compiler differences between VC and GCC are fairly small.) I don't know what language you used - is it something that people would have to pay to get a compiler for?
It's good to look at other RPG rules, e.g. for inspiration, but not to hard to write your own system. (Personally I like to not overcomplicate the rules - it's tempting come up with complex rules, but that's often overkill if the game doesn't make use of those rules.)
Regarding copyright, it's not really clear that game rules are covered. Even in the US - http://www.copyright.gov/fls/fl108.html .
I'd only worry about that if say you wanted copy the instructions themselves, rather than copying game rules. (IANAL!)
A licence that tried to say that the game as a whole would have to be distributed under the same licence as used for the rules would be pretty inconvenient in most cases, as most of the licences for documents or game rules aren't going to be suitable for software. (This is similar to the debate as to whether CC BY-SA for art would also affect the game software.)
And even if the OP isn't trying to make money, a non-commercial restriction on the game would make it incompatible with Open Source licences. (Again, the same thing applies to art - and is why non-commercial licences aren't allowed on this site.)
There's free as in no cost, and free as in freedom - not taking a point of view, but it's important to note that these are two distinct meanings of the same word. Furthermore, "Free Software" (as a term in itself - note the capitals - rather than the literal meaning of software that's free) often refers to that as defined by the FSF (similar to "Open Source" being that defined by the OSI).
I agree with bart's first reply. There are plenty of Free art licences that allow usage with non-Free software (indeed, possibly most of them), so there's not really a problem. But there might be the practical point that some people on this site may be more willing to create art for Free / Open Source games.
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