Oh, you have to go back a very very very long time to find the real howlers. Of the modern ones, I'd say:
- Bioshock's was great but too short, and I hate the moral choice thing. Honestly, you kill one infant child, and it's like the world has a grudge against you.

- Oblivion had the dumbest closing scenes ever, although you do get a giant demon vs dragon smackdown you unfortunately do not get to play as either of these things during it... lame.
- Half Life 2: Episode 2, which at this rate will probably be the last episode in the series. Way to end the game on a complete downer, Valve.
- F.E.A.R. because there isn't an ending. Now that I've patiently played through several hours of completely-non-fear-inducing rubbish in the vain hope that it would get better at some point, the game's makers apparently assume that what I'm really looking for isn't an ending, oh no. They think I want the promise of more. WELL I DON'T.
Of course, all that pales in comparison to some of the earlier gems. I could cite hundreds, but here's my personal favorite:
- C64, "Dragon Ninja" ending. (The game some of you older gamers may remember fondly as "that one where you spend the entire game hopping about because you have to have split-second good timing to hit enemies, and they can't hit you while you're in the air." Seriously, you will never take your finger off the "up" button if you play this game.) After playing through eight or so levels of identical enemies with different styling but the same basic attack, you finally beat the big bad, only to be greeted by no music, no graphics, and the following message:
"Thanks dudes. For saving me. Let's go get a burger! Ha! Ha! Ha! Ha!"
Also if you'd been holding down the fire button, you'd miss even this and it would go straight back to the title screen.
That has to win the thread, right? I mean, there are plenty of similar games from the period with no end sequence at all, or just a couple of grammatically-incorrect lines at the very end. It wouldn't happen later on.
Oh wait... yes it would... step forward, European version of "Cannon Fodder" for the Sega MegaDrive, a console that could usually muster up a good end sequence or several. (As an example, Probotector had FIVE possible endings, most of them awesome.) I can't find the exact quote anywhere, but to the best of my recollection it reads like this:
"You have defeated El Presidente and won the game. Congratulations!"
That's right, two blank lines of white text on a black background, which incidentally is played to the same subdued music you get when you're picking the troops to send into battle. And that's it. There aren't even any credits.
That game took me MONTHS to finish properly, and then that's what I get?!
Seriously, if anybody can come up with a game from the same period or later with an ending that was any more lame than that one was, they deserve to win the thread. Otherwise I think I just got this one in the bag, thank you very much!