Any
Bioware or
Bethesda game puts me to sleep. I generally do not enjoy western RPGs. I could barely make it through Diablo II and that game was actually pretty cool. I have always preferred Japanese RPGs. Games like Fallout, Elder Scrolls, Mass Effect, etc. put me right on the first train to Sleepy Ville.
I'll have to say I agree with all the Half-Life mentions. Left 4 Dead was cool for like the first week, but it became incredibly boring real fast. Same with Portal. I remember finishing the original Portal back when it came out, but I had no desire to replay it. I used to dig
Valve games like Half-Life 2 back in the day, but recently they make me want to eat one of these.
GTA 4 was another. I don't even know why I checked that game out. Back in my 360 phase I was more prone to playing games I normally wouldn't. I played the intro scenario in GTA 4, got that one docks achievement or whatever, turned it off, and never played it again. So fucking boring.
Little Big Planet felt like the biggest chore to play too. I love platformers and picked it up thinking it was going to be cool, but it wasn't.
I think the lesson I learned over the years is that most Western, non-Japanese games tend to put me to sleep, real fast.