I have to agree with a man's word should be good enough.

If you have agreed to sell a game AND TAKEN A DEPOSIT, you've committed to the sale unless the buyer backs out, which should mean that you're entitled to keep the deposit, if so inclined. If there is any doubt in your mind that you may not want to sell a title, then don't put it out there in the first place.

Many of us can share details of deals where we could back out of a deal for numerous reasons, but a real man stands behind what he agrees to. I know the legal definition of a contract will allow people to wiggle out of just about any agreement, but that doesn't make it right. At the end of the day, this is still a pretty small hobby and word will get around of shady deals and people not doing what they say they'll do.