10 Gruelling Video Game Levels That Were Just The Beginning
4. Death Mountain - Zelda 2 The Adventure Of Link
This may not be the very first dungeon, but it's early enough to smack you upside the head with its out of nowhere challenge, making you quake with terror as you realize that you have a whole game left to go.
Zelda 2's Death Mountain is INFAMOUS among NES veterans as one of the most out of left field difficulty spikes in gaming history.
Not just because of the radically different gameplay style of Zelda 2 leaving players still getting the hang of things by the time they reach Death Mountain, but because this is where the game decides to throw most of its mid-to-higher tier enemies at you all at once, in cramped corridors where you're unable to dodge as effectively as elsewhere in the game, and you are definitely not at a sufficient enough level where you can deal with them yet.
Fortunately this is an RPG, so if you keep ramming your head against this wall, you will EVENTUALLY make it through, but such a 90 degree spike in difficulty so early on has forever traumatized an entire generation of Zelda fans.