I don't know where to begin...
As a PC gamer, I never cared for Halo. It was a game chalked full of stuff I had seen before. Nothing innovative. Nothing really fun... but to everyone else it was the birth of the FPS :/ (I'm not interested in "catching" this boat... but apparently I missed it anyway)
Most war games. Call of Duty, Medal of Honor, etc. I can blast zombies and terrorists all day long in Half Life or Soldier of Fortune... but the staple multiplayer games are extremely "MEH" to me. Most likely because I don't care for multiplayer. I want multiplayer games for multiplayer, like Unreal Tournament. When I want a campaign, I go for single player FPS games, and the campaigns in the tripe A FPS games are typically dumbed down due to the multiplayer elements. Just like UT said, we are about multiplayer. We don't really care about single player... I wish some single player FPS games would take the same consideration. There are a few, but it seems the big budget war games can't avoid tacking on a bland solo campaign.
Half Life 2. I followed this game from first announcement and drooled at the potential. The tech demos showcased the environment reacting to my weaponry, Propping a desk in front of a door, luring mobs into fans, knocking rows of barrels onto enemies... I saw one level in the game that this catered to. The rest of the game was a pretty straight forward, (been there, done that) shooter. The one level (which was their showcase demo level) so I had seen it before purchasing, gets about a 95 from me. The rest of the game gets about a 60.
Turn based strategy... I hate it. absolutely hate it. The whole genre. Its the only game type I can't stand. I can play something from any genre or gametype out there... but not turn based.
Steam. Lets forget about DRM. The "selling point" of steam seems to be social tools and trophies. I don't want either of those in my games. Auto patching is bad. always online is bad. Being seen when I want to "get away" is bad. Take Steam's feature list and go bullet by bullet... its pretty much the opposite of everything I'm looking for in a utility. I want the opposite of Steam. Give me a tool called Maets and have it remove adds, block my activity from leaving my PC, locking down games so they don't change unless I do it manually, restrict access to the internet... that is more up my ally.
That should get me started... I've missed a lot of boats ;)