Here is the basic idea!

HERE IS WHAT OUR FABULOUS LEADER MEMESFORTHEMEMESGODDESS HAS DECREED! SO ESSENTIALLY [IN THIS WORLD] EVERYONE INCLUDING MONSTERS ARE EITHER GENOCIDAL (IN WHICH CASE THEY USUALLY HAVE A MASK THAT LOOKS LIKE CHARA’S SMILE), A PACIFIST, OR THEY’RE NEUTRAL (IE: THEY’LL KILL IF NECESSARY.); THE BIG THING, HOWEVER, IS THAT IT’S RANDOMLY DECIDED BY AN ENTITY KNOWN AS “THE CODER” WHICH ONE THE MONSTER IS, AND “THE PLAYER” DECIDES WHICH ONE THEY ARE FOR HUMANS THAT FALL DOWN INTO THE UNDERGROUND.