There's nothing quite like that sinking feeling when you realise you've hit a major brick wall of difficulty in a game you're otherwise enjoying the hell out of. It can be demoralising and, in the most extreme cases, kill the game's overall sense of fun.
But thankfully developers are generally compassionate enough to make the most challenging stuff optional, and in some cases even hide it so well that only the most dedicated players have even a faint chance of finding it.
That's certainly the case with these 10 games, which made players jump through hoops in order to seek out the most crushing, punishingly difficult content on offer.
Needless to say, only the most hardcore and committed players would persevere with these levels - some of which can take literally hours to beat - rather than just having a quick go, noping out, and then moving on with the rest of the main game.
Had these levels been included in their respective games proper, though, let's just say their completion rates would've been a lot lower...
10. Area 51? - Crash Bandicoot 3: Warped
If the original Crash Bandicoot is often cited as one of the most deceptively difficult platformers of all time, the two immediate sequels were generally far more forgiving, especially Crash 3: Warped.
But Crash 3 nevertheless offers up a disc-snappingly difficult secret level which can be accessed by first acquiring 15 time trial relics and then entering the secret warp room (which is first accessed by receiving five relics).
The secret warp room's third level is "Area 51?," another of the game's already-infamous motorcycle stages, with the added difficulty that you're racing against a speedy UFO and doing so in the middle of the night with extremely limited visibility.
Though the N. Sane Trilogy version of the level has had its difficulty nerfed somewhat, the original PS1 article was more or less an exercise in rote memorisation through repeated failure - and an absolutely infuriating one at that.
As much as players rightly complain about how fiddly and annoying the regular motorbike levels are in Crash 3, this bonus one is a piss-taker on a biblical scale.