Can I use Bitcoins in a game?
There is a game that uses Bitcoin as its currency called Dragon's Tale, not to mention numerous online casinos. In general, using Bitcoins in games is quite feasible, just requires a willing developer.

In many cases it can even be preferable, as one could imagine making a simple micropayment in an instant provided they need to purchase something in a game, rather than transfer the money in bulk and later not using all of it without the chance of getting the rest back.

Moreover, similar to upcoming Diablo 3 Auction House Marketplace, or already existing market in Second Life, one can imagine the players earning Bitcoins in such games from other people and later withdrawing their earnings with an ease.