Your game must have the theam of alternate realitys as in... say you are parkouring in a city, but all of a suddon... You are in the same city... but insted humans are fish people.   so make a game that questions and releats to alternative realitys. Have fun with this jam and play with it and tweak it just to make it the way you want... You can imagine your alternitive reality or many alternitive reality combined. Just have fun with it