Hmm, I guess Deadly Premonition is a good example here. It’s grim, it’s goofy, and while it never feels like either is in service of the other, neither steps on the other’s toes either. But maybe you’re talking about mechanics rather than narrative?
If so, I think Katamari Damashii is also a good example. The thing you’re doing is goofy, and firmly tongue in cheek, but the action is actually pretty hardcore - you’ve got to get everything in a certain time period, with penalties for hitting something too large. Especially the levels where you have to “get the biggest cow” or whatever, which means you have to build your katamari up real big, but without hitting any smaller cows which will end the level. And sometimes those cows are basically invisible once you get big enough.
Interesting to think about!