Brink... I have found it to be a lot of fun, lately. I'm not sure what happened in the last three years (I started playing a few weeks ago) that made it one of the most disappointing games at launch to a rather well constructed game now. Even with only 2 or 3 (real) players in my team, I'm getting my money's worth out of the thing. Of course, it doesn't hurt that I paid $5 new for it.
Dark Void is another game that most people hated or never bothered to play. It feels like a PS2/Xbox-era game and will not blow anyone away by any means, but it's not really a bad game, just a generation behind in the gameplay. One annoying stage exists, but everything else plays fine if you have an attention span of more than each passing year.
Eat Lead: The Return of Matt Hazard. Another fun (and funny) game that is in on it's own joke. Again, has "last generation" style of gameplay. But there isn't anything wrong with that if is still plays well, which it does. It has a lot of goofy stuff going for it with different game parodies and satire.
Owner of The NES, SNES, N64, GCN, Wii, SMS, GEN, TG16, PSX, PS2, PS3, XBOX, 360, GB, GBC, GBA SP, GB Micro, DS, DSLite, PSP and a lot of crappy games. --BLINGO!
All 2D shoot-em-ups. (aka "shmups", ugh) A few notable ones: Deathsmiles Akai Katana Dodonpachi Resurrection Radiant Silvergun Strania Ikaruga Triggerheart Exelica
People tend to dismiss them because they are too short, too hard, too simple, or don't have enough story, etc. What people miss is that even though these games can all be played with 2 or 3 buttons, there is a lot of depth, technique, and nuance to learn, and becoming proficient is an enjoyable path filled with personal improvements and discoveries. The old onion / layers analogy is applicable to these games, but most people don't go past the paper-thin skin.
Other: Bangai-O: Missile Fury HD Ninja Gaiden II
These games are often dismissed for being too difficult. The thing is, new gamers think Super Mario Bros. is too difficult today. Strange, because it wasn't too difficult in 1986. There are so many games today that do not challenge players in any way, so people aren't used to applying their creative thinking and problem-solving skills to overcome obstacles. I think that trend is dangerous because creative thinking and problem-solving skills are useful in all aspects of life, not just video games.
Finally: Dark Souls
I get that not everybody likes it, but there are a lot of people who insist that the game is masochistic, broken, or stupid simply because they do not like it. For me, it was a really fun game with a lot of creative environments to explore, and I appreciated how learning was more important than grinding. I don't understand why people feel the need to attack whenever it is mentioned. There are tons of games I don't like, I just don't talk about them.
The Bourne Conspiracy Monster Madness Battle for Suburbia Bulletstorm Wolverine XMen Origins (was 5x better than movie lol) LotR War in the North Battle for Middle Earth Captain America (this one is iffy though)
" Guess I'll have to break the news; That I got no mind to lose "