What are the most difficult games?

I want to try beating games on their hardest difficulty and i'm hoping I could get some good suggestions. New and old games are both accepted.

God of War
Ninja Gaiden
those games are tough to beat

Ninja Gaiden

The original ninja gaiden games. The new ones are tricky, but not super hard. The original ones were as hard as nails.

Are the old NG games rare? I'm not trying to go on a super search to get these games.

God Hand is probably the hardest 3D game I've played.

Maximo is also up there.

DMC series not so much...

God Hand.  The hardest damn game I have ever played.

But the awesome credits and wacky sense of humor made up for the crazy challenege.:P

"Are the old NG games rare? I'm not trying to go on a super search to get these games."

Also, Halo 2 on legendary is damn near impossible.

Even more damn near impossible is Halo 3 on legendary with all the skulls turned on.

Ha, yeah, God Hand. I stopped playing after getting my butt kicked on the second level about 30 times in a row and having to restart.

I need to use my Action Replay and just blaze through that game one day.

I always remember Battletoads as being crazy hard... Ikaruga is tough on expert as well.