I don't think the game overall was gimmicky. I think I just got to a point in the campaign (and I was playing on Normal, not Hardcore), where I felt like the difficulty was plateauing. I don't think it would have lasted if I pushed through it and I can't even remember where I stopped. But, as an example:
Map 1 has an ogre and two rifts
Map 2 has an ogre and three rifts
Map 3 has three ogres and three rifts
Etc. It was a period where the new traps weren't really that helpful and I was getting stuff like the wind gloves, so I got a little frustrated.