I'm going through a bit of a slump at the moment. One of those "all my ideas are terrible, and I'll never be able to implement them, and even if I do, it'll be *boring*" slumps. They happen regularly, and I've learned to wait them out, resisting the urge to, say, chuck all my code and start from scratch, or chuck all my code and design a new game, or chuck all my code and give up game design FOREVER in despair.
Most of the slumps go away relatively quickly, so I'm taking the opportunity to step back a little. (Fixing bugs is making my fingers itch to chuck all my code, or at least major parts of it, and that's never a decision to make during a slump.) So I'm spending my spare time reading, and occasionally doing something radical like going outside.
The nice thing is that these slumps are almost always followed by periods of drive and innovation, so I'm hoping that happens this time, too.