Trine 3 was so disappointing after playing 1 and 2. A friend of mine and I have had the same problem, finding another great co-op game like this.
Couple of games to throw out that were fun:
Borderlands 1 & 2 (skip the pre-sequel), there is a really entertaining D&D DLC for Borderlands 2.
Rogue/TurnBased/RPG-ish: Dungeon of the Endless
RPG: Neverwinter Nights 2: Platinum
Lara Croft and the Guardian of Light (2 player)
I was hoping they would have a XCOM 2 Coop Mod out by now but no idea on when that'll be. Originally said February but no info out there since then about it that I can see.
