M2TW - bought it when it came out, went hunting for a better video card to play it, and just never got around to installing it. Read the local reviews and impressions here at the Org, and realized that it's probably not worth starting up (especially with my limited gaming time). Didn't buy the Kingdoms expansion, so I probably couldn't get any use from the existing mods.

Doom3 - played it some when it came out, but my PC was woefully inadequate at the time. This meshed with the video card search mentioned above. Once I upgraded, I just couldn't get back into it. I've come to realize that single player FPS's are just not my thing. Especially when duct-taping the flashlight to your firearm is not a built in option.