I've sold a couple dozen games and never taken a deposit from a potential buyer, nor been asked to take one.

Conversely, I've bought several games out of state/country that I've told the sellers "I can't get the game til this weekend, I'll send you $100 or $200 deposit, please consider it sold, remove the ad and if for whatever reason I don't take it, you keep the deposit."

I've never had anyone say no, and never not bought the game.

In this particular case, my first instinct is you held the game for a long time, he backed out of the deal, so he loses the deposit. My 2nd instinct - the guy knows where you live, the money isn't gonna change your life.......

Just the same, i'm gonna lean towards the first instinct. It's a cheap life lesson for the buyer, and it's probably not gonna change his life either.