Most annoying game endings...

[Spino]

Half Life's gameplay & story started really strong and ended poorly. Those final levels on the alien planet were just silly and the final boss battle was god awful! Wait, I have to destroy the evil giant alien baby boss by bouncing on alien mushrooms while pumping rounds & grenades into it's exposed brain... WTF?!? However, I did love the very end of the game, the final sequence where Gordon is teleported back to the tram and the man in the suit presents him with a 'work for us or die' ultimatum. So technically speaking Half Life's ending (post-gameplay) was pretty good.

Half Life 2: Great gameplay... awful plot & story. For a game four plus years in the making I was a little shocked & dismayed to see a storyline so recycled & silly that it could have easily passed for a Sci-Fi channel made for TV movie. However as with HL1 the post-gameplay ending wasn't too bad, the man in the suit stopping time and appearing out of nowhere gave me a smile. Pity the annoying girl/love interest didn't perish in the blast because they're bringing her back in the expansion... yaaaayyyy

[Fragony]

Half Life 2: Great gameplay... awful plot & story. :

Gameplay wasn't that good at all, in the first the AI put up a decent fight, in the second they just stand and shoot or hide behind explosive barrels. Fighting just wasn't fun.

but, grav gun is brilliance.