Play any devil may cry on hard (not DmC, that game is a bad joke) or pretty much any other hack n slash. Thats a serious challenge right there
DmC was actually pretty good. Dante Must Die! mode was crazy hard and don't get me started on Hell or Hell mode. Never did beat that mode, It really tests your skill, Enemies have standard health, but Dante still dies from one hit! WTF!
Then there was DMC3 Dante Must Die mode, which was EPIC and sick at the same time. Till this day I still don't think anything was harder than beating Ninja Gaiden Black on Master mode and completing all the missions in mission mode. Even Dark Souls can't compete with that.
Tbh dark souls did spoil me for a while. It was hard for me to get into other games after finishing it. I remember playing dark souls 2 waiting for infamous to come out. I played infamous for an hour and went right back to ds2 and played it for months.