I'm not sure what the hardest games for me have been. There are some that are hard for all the wrong reasons, and those on the opposite end, and then more in between. Borderlands has been one of the former, whereas I'd place Super Metroid as one of the legitimately challenging games out there. Earth Defense Force 2017 can get pretty hectic, but you can kind of bypass that with enough armor grinding.
Mostly it seems to be RPGs that get me. Chrono Trigger and the Paper Mario games have been a bit easier, but stuff like Final Fantasy 4, 5, and 6 kick my *** at least at one point or another. The farthest I've got I think has been ExDeath's castle.
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About suffering they were never wrong,
The Old Masters: how well they understood
Its human position; how it takes place
While someone else is eating or opening a window or
just walking dully along...