Program a game in a week?

There are many great resources available to small, budget-conscious independent game developers today. On a public forum, in a counter-rant, I expressed this fact by bragging that if you gave me a week, a fresh install of Windows, and a good Internet connection, I could build a halfway decent game with no budget whatsoever. No, it wouldn't be able to compete with Halo 2 or anything (if I could create that kind of game in a week, I'd quit my day job), but it would be reasonably amusing and playable.