Not necessarily rage quit, but there was frustration quit indeed.

Torchlight, the final boss. (Spoilers to Torchlight ending follows!) I don't know if my alchemist/mage build was too badly made, but I juts couldn't kill him. I started resorting to leaving the room, get back in shape and reenter, but there were times when that would reset the level from scratch and all my work was lost. Eventually, I got tired of trying, went online, and saw what i was missing on Let's Play videos. The girl comes down, kind of congratulates me, a wall of text appears and... you're back in town from the start, ready to fight at a higher difficulty!

That was it? THAT WAS IT!?

I uninstalled the game and considered it finished. At least there was an awesome movie at the end of Psychonauts, which pushed me to finish the Meat Circus.

Quite recently.. that god-damn racing level in Mafia. I hate it!

That's actually fairly easy. Just don't push too much and stay away from the curbs. Aggressive driving will inevitably send you into a spin, consistent smooth driving wins the race...

Never, I only ennuiquit games.

Came close with Strike Suit Zero a couple of days ago. It controls fairly well, but with loads of enemies flying around it's easy to get pummeled without any idea of where it is coming from. Which wouldn't be so bad if trying again meant you had to replay the section, but it makes you start the entire mission over. The consequence for failure is a bit on the old school side, and I don't have the same kind of attention span I had when I was a member of said school.

It wasn't a "rage quit", but before that I hit a wall with the Witcher. Everything was fine until it was time to fight the Hell Hound thing. I thought I had sufficiently grinded, but it tore through me like I had only been playing for 5 min. Then to try again I had to click through the mob scene leading to it only to get slaughtered again. After repeating that about 5 times I gave up on the game entirely. I was getting into up until that sudden, inexplicable rise in D.

I think you can take a shortcut there. I mean one that saves you much more time than the penalty you get.

If a game ceases to be fun for stupid reasons I regularly quit and seldom play it again. There's too many cheap tropes in games sometimes. These are all ones I've got pissed off with and quit at some point:

Infinitely respawning enemies (Killzone series.)
------Bosses that take ages to whittle down to low health then hit you with a super 1 hit KO or near KO move (FFXIII !)
Regular enemies that instakill (Resistance series.)
------ Client side hit detection (Battlefield 3)
Ad Hoc Multiplayer (Coming from Xbox/PC to Xbox 360 has been an utterly disgusting experience, so unbalanced.)
------Poor Camera (Jak & Daxter)
Badly Scripted on rails sequences (Ace Combat: Assault Horizon... try the AC130 mission on highest difficulty ¬_¬)
------Stupid/Cheating AI (newer Total War games... makes me scared for Rome 2)
Higher Difficulty just means more accurate enemies, stronger bullets (tonnes of games but Call of Duty is terrible for this. I like enemies to get more tactical on higher difficulties, not just shoot more powerful bullets. Bungie Era Halo games did this well.)
------Bad Checkpointing (again too many to mention.)

Seems like a huge list but I'm an avid gamer and there's a huge list of games I've loved and never had any major frustration with.

I play games to enjoy and have fun mostly, or be immersed in a story, when a game gets too frustrating then it ceases to be fun.

Rarely do I ever rage quit. Occasionally I'll rage quit in LOL if the vast majority of the team consists of duo-queuing adolescents who are being douchebags.

If it's the AI that's beating me, I'll possessively stay in front of the screen for hours until I walk away victorious.

In Syndicate Wars today... That's just ridiculously hard game, though I managed to beat the level I ragequitted on. Took me about 10 tries. Still one of my favourite games to date :-)

(Btw what's the meaning of those bars under the healthbars and the little thing under power?)
Still suck at this game

I hate that too, multiplayer should be played on dedicated servers, period.

Hotline Miami. All the time.

Seriously, I don't think I've ever exited that game because I had something else to do or had finished playing. It's always "ARRRGH!! Why did I ever install this stupid thing! Let. Me. Out!" Then the next day, I start it up again. Sigh.

I must confess.
Some time ago when I tried Warcraft III, I kinda rage quit at some point.

Prince of Persia: Warrior Within. Bad checkpoints, but I´ll try it at some time again.

Don't give up! I have yet to complete the game, but it's on my to-do list!