When you can't even be bothered to go though it with unlimited hits/god mode.

Yup you nailed this right here - later battles are very much about "solving" them as you put it - finding how you should approach it tactically (usually after a few losses) and creating a deck to match.

As I don't wan't Card Hunter to forever dominate the thread, here's another example of this happening to me - Lionheart: Legacy of the Crusader, years ago. I'm not quite sure where I screwed up, but eventually my ice-focused mage was just worthless in combat. I loved that game, especially the first act in Barcelona, but it was impossible to finish with the character I made. I'd have to star all over and I hate doing that. Made me wish the game had an option to "refund" all the skil points, though I know it wouldn't really make sense.

When it gets tedious, I will try to push through frustrating parts as long as it's because of skill gap or if I'm yet to learn attack patterns and so on but if there's enemies that I have to continuously hit away while chipping next to nothing that's where I quit. Hollow Knight was a recent example, liked it very much until watcher knights who have 1320 health compared to my Blade with 13 attack. It was too tedious for me to fight an enemy like that so I quit.

If you're enjoying yourself then there is no reason to quit even if you suck. If it's the 74th time you restarted the part off a game because it only has checkpoint saves and there a few very difficult part before the next checkpoint than I say F it.

Of course these days are not like when we had to go kilometers uphill in the snow to the arcade to play games, there is a lot of resources on the web: strategy guides, walkthrough , cheat codes, save games even. Those are worth checking out if you really like the game but can't seem to get better at it.

Was it the flight simulator on the Atari/Apple 8bit computers with 5fps? Or was it something like Microsoft flight simulator?
Uggg... not the hardest of games but annoying as hell.

In adventure games, when more than 1 solution becomes ridiculous I'm very likely to quit, because what's the point thinking about it if the solution is contrived anyhow.

The game that I thought of when I saw your post though was DUST. I made myself uninstall the game because even though I loved what they were trying to do, I just found it frustrating trying to complete the tasks. Initially having all kinds of problems with the path finding of the people in time constrained situations, especially their inability to cross even little bits of unlevelness in terrain so that I was always watching and babysitting while fighting off waves, fires, rising tides, etc. But the level that got me to quit was a difficult lava level that I struggled with and hated, and then once I completed that level I was greeted with another level that featured even more lava. I was wanting to get through the game so I could get to the sandbox mode where I could just play with the terraforming tools, but I made myself quit and was better for it.

Unfortunately I can't remember the name, or even if I ever knew the name of the game. It was on my friend's computer and I'm pretty sure it was a DOS flight simulator.

https://www.youtube.com/watch?v=CGUtAJRsfTg

I don't think that was it no. Judging by some screenshots I think it might've been
http://www.mobygames.com/game/dos/microsoft-flight-simulator-v40

Quitting? Quitting is for losers. You'll have to pry that controller from my cold, dead hands. I do go on really long hiatuses, though. Especially, when I need time away from a game.

It's time to quit when you are no longer having fun. Being bad or good really shouldn't be that big of factor in single player.

I quit a game if I've
1. Spent an absurdly long amount of time on one level without beating it
2. I've tried every innovative or even obvious strategy I can think of, with no success, and I've tried my very best
3. I've tried taking a break and coming back to it several different times on different days

If all these things are true and I still am no closer to advancing, at the very least in the main story, then I basically say it's not worth my time and admit defeat. But I also second qwixter. If it's not any fun why bother playing any more?

EDIT: Sometimes I've quit a solid game because it was fun, but the first try on one game mode,(Original Starcraft: Skirmish mode) where I've had so much fun with similar games, was such a pain that I lost interest. The way I've heard it described is that "Starcraft makes you micromanage" to succeed. I agree, and I don't like doing that so SAYONORA.

I think you've given an answer for your own question: That's how it works for me at least ;)

Prince of Persia (2008) had a boss called The Warrior who kept kicking my ass and I just couldn't beat him no matter what. It was late in the game but after trying 25 times or so I just said: "fuck it" and quit the game and uninstalled it. When a game stops being fun and begins to feel like work/chore that's when I quit.