Nothing quite like the satisfaction of having something work just like you wanted. Its true no matter what field you go into. When it comes to making your own game, its something you get every day. I'm a week into mine, just now implementing my game's (a turn based strategy) combat mechanics, and I can get drawn in. Monday I sat for four hours straight working on converting the basic collision detection between units to implement some damage dealing combat. When I was done though, I was ecstatic. Yes there were still minor bugs, but in the scheme of things, I'd accomplished something.