I have made (but am still working on) a mod that adds Homestuck creatures and items and symbolism and languages and buildings and SBURB game mechanics to Dwarf Fortress.
In the mod, you play as Trolls. After all, making a mod where you play as humans would be boring and lazily-made! Besides, the mod started with being made exclusively for trolls.
For those of you who don't know, Dwarf Fortress is a mind-bogglingly complex game rendered entirely in ASCII. (well, technically, not rendered in ASCII, but rather, in SDL emulating CP437)
You can also play it in graphics! There's a graphics version available for download here.
The main topic on the DF forum is here.
How can you contribute? Simple! The raws are written in plain text, using simple "tokens". The tokens and an explanation of what they do can be found at the wiki. The raws for the mod itself can be downloaded here.
What does it contain as of now? Quite a lot. 14 castes of troll (13 blood colors + winged trolls) lusus out the wazoo, beforans, dersites, prospitians, underlings, grist, god tiering, Lord English, dave_ebubbles, the works.
What's next? Iono.