Socom Confrontation (I was huge into Socom 2, over 1000 hours played in 3 years, but Socom 3 and this were awful)
Mass Effect (Boring, didn't really like the characters, framerate annoyed me, but I sold it for 40)
Quantum of Solace (only paid 10 bucks, not worth it)
CoD MW2 (Only that I bought the Prestige Edition. The NVGs are kinda nice but I don't play the MP at all, it's nowhere near as fun as CoD4 was. Too much aerial deaths and people camping like bitches)

A long list of games that I regret purchasing over the years but the most recent one I can think of was Final Fantasy XIII.

Final Fantasy XIII was total garbage. It was so boring and cliche'. Story/plot - crap it does not make any sense. Same line repeated over and over: "Cocoon, fa'cie, l'cie, Pulse, focus , focus, focus". . Battle system- frustrating. Fighting the same stupid enemies over and over. They should of used a full real time battle system or a true turn baseed system not a half and half battle system. Gameplay- boring, too linear and the battle system was not fun at all.. Characters in the game- poorly developed and they knew what was going on but the gamer does not get told what is going on. I did not get far in the game only 8 hours in but it was a struggle for me and only on Chapter 4 or 5 in the game.

I came so close to breaking the game disc out of frustration. But I returned it for a full refund.

Halo ODST( fell for the bullshit hype/reviews )

Killzone 2 ( fell for the bullshit hype/reviews )

SSBB ( fell for the bullshit hype/reviews )

Metro 2033 ( Really Bad )

Halo 3 ( fell for the bullshit hype/reviews )

The Last Remnent ( The worst jrpg ever )

Gears of War 2 ( fell for the bullshit hype/reviews )

Forza 3 ( fell for the bullshit hype/reviews )

I don't trust half the people on this site. They are so full of fanboy bullshit you can't weed out the good non biased opinions from the fanboy ones.

Oh, totally off-topic, but I want to join this too.

1. FF6

2. FF10

3. FF7

4. FF4

5. FF5

6. FF12

7. FF2

8. FF3

9. FF1

10. FF8/9 (equally last for me)

FF8 was WAYY too angsty/emo-y. That atmosphere bothered me the entire time I played. Not sure how I suffered through almost the entire game. That said, I LOVED the card game in FF8.

FF9 would have been MUCH higher on my list except 2 things bothered me. A) The back of the box has a headline "The crystals are back!" or something, as if trying to make it out to be a big deal, so I was like "cool! going back to FF roots!" and got really excited about it. Crystals had nothing to do with the game at all, except maybe the crystal world at the end.

B) The last boss pissed me off. So you beat Kuja, and suddenly this other guy, with no foreshadowing or hints to, just suddenly appears out of nowhere. It was like FF4 (with a more sinister bad guy behind the scenes the entire time) but without any of the build-up. Add in the fact that he was one of the easiest bosses in the game and it just felt pointless.

So I can add FF8 and 9 to games I regret buying and playing.

Actually, I kind of regret getting MW2 as well since it's inferior compared to CoD4. The same game but worse? It has no place in my library.

So my revised list of games I regret buying:

Too Human, FF8, FF9, Scribblenauts, Blue Dragon, MW2. The list gets bigger the longer this thread goes on =P

Endless Ocean - Thought it would be a nice change in gaming... Horribly boring, sleep inducing game, worst purchase ever.
Far Cry 2 - It just didn't play well, the map is too large for the game itself.
LittleBigPlanet - Just not my type of game, i tried to like it but i couldnt get pass how simple and unfun it was.
Fallout 3 - Yeah, no more WRPG's for me, Sticking to JRPG's from now on.

Probably more but for now thats all i can remember.

FF13
MW2

is there someone counting the number of appearances by game / editor / platform ?

Final Fantasy Tactics Advanced - I thought I'd try it cause I had already bought all the FE and Advance War games.

I'd throw Zack & Wiki on the list, but I actually wish I bought more copies as I made $14 profit by selling it over a year later.

Socom Confrontation at launch (lag, glitches, bugs, controls)
Some of my xbox live arcade games :/

Battlefeild: BC2. Not because its a bad game but because i dont have time to play it with all the games that i just got :( I wish i would have waited until the price dropped a bit