I'm forever chasing the high that "NGU Idle" was... "Wizard and Minion Idle" (WAMI) scratched the itch for a bit, but NGU is just something special
My other fav is IdleOn MMO, with Idle Skilling as its little sibling game. I haven't played in a couple years though, so I'd prob have to start over, they've just added so much more stuff to it.