Cosmic Horrors Jam is a two-week jam where you make a cosmic horror themed video game or physical game. If you don't know what Cosmic Horror (sometimes known as Lovecraftian Horror) is exactly, put simply it is a horror sub-genre that as Wikipedia puts it: that emphasizes the horror of the unknowable and incomprehensible more than gore or other elements of shock. A sub-genre that emphasizes themes of cosmic dread, forbidden and dangerous knowledge, madness, non-human influences on humanity, religion and superstition, fate and inevitability, and the risks associated with scientific discoveries.
Your game can be any genre, made in any engine, for any platform (though making it playable on PC is preferable so that it can be shown on the live stream) the only fundamental rule is that it should be a part of the cosmic horror genre. Make a classical Lovecraftian mystery, an Elder Thing virtual pet, an insanity simulator. The possibilities are endless! Just remember that your Cosmic Horror creations can be solely original you don't need to use the creations of the Cthulhu mythos or other Cosmic Horror writers (Clark Ashton Smith, Robert E. Howard, etc.).