[Graystripe2000]

I have. Yesterday, I was playing Super Monkey Ball 1 on expert mode. I got to stage 42 without using a continue. I wanted to warp via the red goal, and after falling two or three times (I only had 1 life left by the time I made it), I finally got to it and it let me warp to stage 45, THE EXACT SAME STAGE I WAS HOPING TO AVOID WHEN I USED THAT WARP. That convinced me I needed a break from trying to 100% expert mode in that game (which requires you to beat the main stages without using a continue, then beat Expert Extra without using a continue).

[Voka~Daemyn]

Yes but mine is more a different kind of cheated. a long time back when I was younger I rented a game called thunder tanks or something for PS2.

Well anyways I beat the whole game in about roughly 30 mins <_> yes it was that short.

I was pretty irritated that day.

Aside from that. 90% of free 2 play games and Biased as hell RNG for ANYTHING

[Fennekin]

SSB4, G&W's 9 RNG.
Words don't express how frustrating it is to get KO'ed at 10%. 

[Mobotropolis]

I made it to Bowser and the Dark Sky, paused, and my sister beat him before I returned.

On my first playthrough of Monster Rancher 3 my monster died of old age one week before the Event you absolutely must win. You must win this battle because your Rival gives you an important item you need to advance the plot. If you lose you are supposed to, in theory, be able to find the item during next month's exploration session. Unfortunately, there's a game breaking glitch where if you search where the item should be it tells you ... where you need to go to find the item. So though you can play the game indefinitely you'll never be able to reach the end. I had to start over.

On the second playthrough my monster died two weeks before I could activate the event for the Final Battle.

The Chao Garden of Sonic Adventure 2 had a sorry tale. My brother opened all of the initial eggs by throwing them against the wall (abuse). I took one of the Chao and raised it into the strongest Chao in the garden. Once I heard about them I decided to aim for a Light Chaos Chao so this Chao could live forever. Unfortunately ... because the Chao was abused at the first stages of its life it would not reincarnate though I took very good care of it. The sad part; when a Chao that is loved dies and does not reincarnate it shakes its head as it vanishes. I tried soft reset to get into position where I could grab the Chao and take it to the Daycare where it could " live " indefinitely. No dice. The death animation started as soon as you entered the Garden.

And that's why I don't raise Chao anymore.

I could probably write a dissertation about disappointment during my ten years playing Neopets.

[Artsy]

In Ratchet and Clank: Going Commando, there's a segment with wave after wave of enemy (it's ridiculously slow) that's immediately followed by a very difficult platforming challenge. Fall once and you have to deal with the unreasonably slow segment again. Honestly checkpoints in that game were just one big frustration after another.