Thank you! They're really nice. I've just started a new project and i plan to use them in it. :)  For those who are interested, I've made a (very ugly) python script to convert all sprites into spritesheets and add transparency so it would be easier to use in my project. With the script you can modify the position (row and column) where each image should be pasted into. The code is here: https://pastebin.com/besPa147 I also attached an example.