There have been entire classes of games built using GTP engines.
But along with people trying to get GTP to code (and honestly, it is pretty good), they have got it playing board games and the like, some online.
They also have been using it for NPCs in TTRPGs.
Basically once you have something like GTP, you do spend a lot of time just playing around with what it can do.
Especially since you can now run quite large models on cpu’s now, sure they are slow as hell, but you can do quite a lot with that.