two things:

1) it should be multiplat

2)it should be a relatively famous/anticipated game.

you can't name games like Karaoke Revolution Presents: American Idol Encore 2

ok for me it was Farcry 2.I thought this game will be shooter of the year but it let me down big time.

Alone in the dark hands down

GTAIV.

No contest.

yeah I also had high hopes for Far Cry 2 but the open world style has hurt the game's fun.

Propably alone in the dark.

This is the correct answer.  It was horrible on all of the systems.

I would say The Force Unleashed. It wasn't bad, but it certainly wasn't as good as it had the potential to be.

GTA4 was disappointing, but again, not bad.

That's it, really. I suppose Bad Company could have been a LOT better, but I didn't have very high expectations for it, being made by EA and all.

Alone in the Dark was a franchise killing train wreck.

GTAIV was very far from the worst. Overhyped and overrated, sure, but bad games don't sell as well as GTAIV did and it was no worse than any other GTA game since GTAIII.

GTA IV

Very disappointing

I agree with Alone In The Dark.

Even the 'fixed' version for the PS3 was god-awful.