I agree, House of Crom is the closest thing you can get to what you have in mind lots of bosses big big dungeon you can kill a few bosses and take a small break and continue. It's not mandatory to kill bosses in order nor you are on rails you can choose where to go and which boss to kill.
I don't know how far in CoX you leveled but damn good game it was godam NC Soft for killing it off. The frost fire was in Hollows and yea I remember sliding on those icy slopes. Dungeons where really cool desigend in that game.
Remember the Terra Volta respec trial in reactor? That was a blast.
I miss CoX so much I am ready to pay couple hundreds if they bring it back. Alas it won't happen. NC Scumbags...