These are some tiles I've modified based on OptimusDu's modifications of Clint Bellanger's First Person Dungeon Crawl Art Pack and XCVG's Ascension Adventure Tiles.

From https://github.com/clintbellanger/heroine-dusk "The visual art for Heroine Dusk is released under CC-BY-SA 3.0, with later versions permitted."

From https://github.com/XCVG/collapsar/tree/cerium "All visual art derived from Heroine Dusk or created specifically for Ascension: Adventure is released under CC-BY-SA 3.0, with later versions permitted."

Made using GIMP.

These are intended for mines or other cave systems.  It adds rocky textures to the Dungeon Tile walls, floors, and ceilings.  There are also wood textured pillars.

Copyright/Attribution Notice: 

Heroine Dusk is created by Clint Bellanger http://clintbellanger.net Ascension: Adventure Tiles by Chris Leclair/XCVG (xcvgsystems.net) [CC-BY-SA 3.0] based on Heroine Dusk by Clint Bellanger (heroinedusk.com) [CC-BY-SA 3.0]