Toribash
I really really really really really really really really don't like Erthtk. HOWEVER, as I started getting better at the game I realize the fundamental understanding on why Erthtk is a great mod, and that is because the mod showed me what I was really mad at, which was myself for not being able to play slowly and think 2-3 moves ahead of what I wanted to do.

As much as I dislike the mod, I feel like it's fun to play once I understood what I was supposed to be generally doing.
"As the legend goes, the Felnin will be reborn time and again, though not always in the same body." - Fels.