Ashes is a Post-apocalypse themed total conversion for the GZDoom engine. It combines old school build style level design and Doom style action with a twist of Stalker and Fallout.
Features:
- 2 full episodes and an expansion offering dozens of intricate maps to explore, scavenge and fight through.
- A deadly arsenal of weapons from lowly 9mm pistols to improvised garage railguns.
- Fight varied enemies including: insane bandit raiders, mutant cannibal warlords and acid spewing carnivorous plants (protip: bring your flamethrower).
- An absolute banger of a soundtrack by cacoward winning musician John S.Weekley (aka PRIMEVAL).
Search GzDOOM and FreeDoom, with which ashes is made+community made wads. Ashes normally is only a mod for the original DoomII engine, but this standalone version use the GzDoom engine and FreeDoom, both FOSS. Apart use diferent wads, not the original Doom Wads, which are proprietary. Its similar to The Dark Mod, which in it’s first version was an mod for DOOMIII, but with v2 it becomes standalone with the own DarkRadiant engine (OpenSource) and community made Missions (in more than 120 missions so far created by different users of the community it is impossible for there to be a unified license, depending on the assets they had used).
https://en.wikipedia.org/wiki/The_Dark_Mod
That does not mean it fits the open source definition , that you can change it and even sell it
Unclear licensing can be a problem , see for example how cataclysm dda had to remove a tileset due to it.