Well guys, what is it?

Count me in the Demon´s Souls camp.

Sesame Street Once Upon A Monster, for sure!

Bayonetta on Climax Difficulty, makes Catherine & Castlevania on hard (& platinuming atelier rorona) easy comparitively & a totally different ballpark to the 'souls series & even (the much more difficult) Monster Hunter series imo. Still havent come close to beating that one (Bayo).

Such an amzing game though, it'll be a long term affair, much like nethack (where i've made it 9 levels in 15 ish years!)

Donkey Kong Country Returns
I died frequently in that game :/

Is that a xbox360 game that uses kinect?

Yes it is.

Killzone 2, it was just such a rubbish game I kept getting migraines preventing me from playing it properly :-p

If we include high difficulty settings then it's probably the highest difficulty on The Conduit, closely followed by Deadly Creatures.

If using the default difficulty (which helps put more games on a level playing field, as some games don't have different difficulty settings) then I think Zack & Wiki gets top spot, perhaps tied with Toki Tori if that is allowable (it's on WiiWare so it is kind of this gen, but I think the same game may have been on GBC first, or at least a similar game)

Street Fighter IV (also, Super & Arcade Edition).

Very hard/technical game to master and be truly good at.

Without a doubt, it's Dark Souls for me.