They could incorporate a lot of the show into simple game mechanics too. The ability to split molly and scratch up with the curse acting as fast travel to get scratch back or to restart a puzzle only he can do. The ability for scratch to possess things, the fact only he can go into the ghost world so you can have maybe bonus levels or secret areas in there you can only access as him. Scratch already loves food so a food=health mechanic would work perfectly and be able to be incorporates very naturally (i imagine he hides snacks all over the house which the player can find). You can have darryl be your item store and its played out like a mock drug deal, you could have libby offer hints because shes into playing detective...
It doesnt even have to have an original story, just a few missions playing out episodes of the show with battles added in could work. Mostly just as an excuse for in-between scenes of the characters bantering abt whats happening because molly and scratch are unironically very funny together when they're just talking and i want more of it
