What's the hardest game you've played?

[SIZE="1"]Most ROM hacks that I've played are keyboard-smash-hulk-rage hard. Examples include Kaizo Mario 1 / 2, Super Metroid Impossible, SM Limit, SM Redesign, Legend of Zelda: Parallel Worlds.

Normal games... I'd say Metroid Prime 2 Echoes on Hard at some points was infuriating. Everything takes like a bajillion hits to kill. Much h8 for the Boost Guardian as well. [/SIZE]

The boss you kill to get the spider ball was a pain in the ass as well.