Getting all the gold medals for Blast Corps back on the N64 was a complete nightmare. I spent so much time on that game as a 10 year old.

Perfect Dark mode on Perfect Agent was like a vacation in hell too. Luckily I trained my little brother to be the best shock trooper co-op buddy ever at that time so we somehow got through it. Also, all of those combat simulator bullshit challenges were insane.

Mass Effect 2 on Insanity was the most recent hard game I played through, and I'd say it ranks up there too. Krogans can push your shit in quick, and maaan was being a Vanguard quite the bad idea there lol. Inferno ammo saved my life.