When was the last time you really felt happy after buying a game?
I usually feel happy after buying a game. It's after I play it that I stop being happy ;)
Probably Dreamfall:The Longest Journey, or if not Indigo Prophecy. They're two of the very few games I've played through to completion recently. I played Tunguska: Secret Files through to completion too, but it's not as polished in the plot or dialog departments as the other two.
I bought Sam and Max yesterday, but I haven't had time to play it yet. Too busy trying to get my GUI and form editor improved. Plus I've only just reformatted and I want to get all my work-related software back in shape before I start loading games again.