SpaceChem
Bought it as part of the indie bundle, but it is good enough that I will also consider buying the physical copy from Zachtronics after I finish the game.
Moto Racer 2
At first, I didn't like this racer. After playing and enjoying Moto Racer tremendously for a long time, I installed this, played for a few hours and it felt as a leap backwards in comparison to the predecessor. Then I uninstalled and considered it as one of the "mispurchases".
However, I recently reinstalled the Moto Racer to share my record times with somebody, and - luckily - also casually reinstalled the second; because while I played Moto Racer 2 with keyboard before, the game becomes a whole lot better experience with the X-Box controller for Windows.
There are many built-in tracks, but in contrast to the first Moto Racer, they are more than less mediocre (and forgettable) at best. So now I use the game mainly to design my own tracks and championships with the editor. I have a lot of fun both creating and racing those.
Icewind Dale II
It's been taking space on the disk for a while, and the party-making part is done, but I just can't get into it, for now.
I finished the first Icewind Dale thoroughly weeks ago and, even though it had its moments, it wasn't really an experience I would care to ever repeat.