Game suggestions?

My little guy is a joy. He likes to play, of course, and whines when we don't play with him enough. (A good reminder to get my duff off the couch).

Anyway, our biggest energy expender currently is go to for a walk. Unfortunately, he doesn't like the heat very much, so some days we can't go out at all.

He doesn't always want to play fetch with his ball, and I don't always have the energy to chase him around the house (which is really fun when I'm up to it).