I really hate to not see the end of a game I've put significant time into, so I usually stick with it even when it gets crap toward the end or it gets crazy hard. There are a few exceptions though:
I gave Giana Sisters: Twisted Dreams the finger tonight after trying to beat the final boss about 25 times. 25's not that many, but I was also convinced that the game had bugged out at this point. To kill this boss, you basically have to avoid a flaming rock he throws at you for a minute or so until it loses its flame, then jump on it to send it toward the boss to hurt him (3x kills him I believe). Well, I did that once on try #5 or so. On my remaining ~20 attempts though, the rock kept disappearing as soon as the flame went out. I had no desire to play through the entie level again to find out if it was a bug, especially since the boss was pretty damn hard even when things were working properly.
I never did finish a campaign in Shogun 2. I managed to take Kyoto and become Shogun... but there was no way in hell I was going to hold it for a year, let alone hold all my other regions who had to donate their armies to my Kyoto takeover.
And lastly, Metal Gear Solid: Peace Walker (PS3 re-release). It seems you can get screwed in this game if you don't build up your arsenal in the right way. I got to the second battle with Peace Walker with only a crap quality missile launcher and no way to upgrade it before the fight. I could barely make a dent in it before dying.
Interestingly, I actually rather liked all of those games until those points.
So what have you given up on because it was just too hard?
I gave Giana Sisters: Twisted Dreams the finger tonight after trying to beat the final boss about 25 times. 25's not that many, but I was also convinced that the game had bugged out at this point. To kill this boss, you basically have to avoid a flaming rock he throws at you for a minute or so until it loses its flame, then jump on it to send it toward the boss to hurt him (3x kills him I believe). Well, I did that once on try #5 or so. On my remaining ~20 attempts though, the rock kept disappearing as soon as the flame went out. I had no desire to play through the entie level again to find out if it was a bug, especially since the boss was pretty damn hard even when things were working properly.
I never did finish a campaign in Shogun 2. I managed to take Kyoto and become Shogun... but there was no way in hell I was going to hold it for a year, let alone hold all my other regions who had to donate their armies to my Kyoto takeover.
And lastly, Metal Gear Solid: Peace Walker (PS3 re-release). It seems you can get screwed in this game if you don't build up your arsenal in the right way. I got to the second battle with Peace Walker with only a crap quality missile launcher and no way to upgrade it before the fight. I could barely make a dent in it before dying.
Interestingly, I actually rather liked all of those games until those points.
So what have you given up on because it was just too hard?