itch.io

It has to be dark enough to not be able to see yourself within it to turn you. You could also just partially turn and keep your sense of self if your strong willed or it could just kill you if your frail enough. They emerge from the darkness when its night or if its dark enough in the area for them to stay out of direct sunlight. 

When in the dimension you can only see darkness and shining light to it causes it to not exist, so its impossible to tell what it is. It could be an alien affliction or a magical phenomenon, I like to leave a lot of the greater world mysteries to the dm but I'd like to think of it as some ever-present organism that is doing this that isn't even aware of what its doing. Living things are transformed into monsters and machines go haywire within it. Everything that emerges from the dark changed will come back looking like they are made of a thick black goop and it taking the form of either one of the common monster types listed or something custom the dm comes up with. Skill checks are done on a d20 and for them to pass you need to get higher then 10 and every + or - you have in that skill is added to your final roll. also the roleplay is more human oriented as your essentially just a mostly normal person trying to survive this apocalyptic world. Sky is the limit with the things the monsters and people in this world can do as the nothing gives them ways to adapt to certain environments but it also just gives them random abilities and appendages as well, some have black tarry wings and others are giant unmoving masses of flesh and goop.

Not much additional to know other then that the world is in a modern day setting, it can be done in any age tho. The Non-existance is essentially a pocket dimension that slowly transforms anything and everything that enters it. People who surive their encounter just say they where in the dark. Also i cant access the files rn but when i do i can get back to ya on how the checks go but the roleplay mostly revolves around trading and talking with survivors who still have groups and settlements set up. Tbh im just super happy yur givin the game a look, thanks a bunch friend.