Critical wave? Really?..heh I always thought that was a poor dual stick shooter. Nothing even compares to meteor blitz.
I have a bunch of favorite games. Land Air Sea Warfare, GTA CTW, Tilt to Live, Space Miner, Angry Birds, Jet Car Stunts, , CoD Zombies. Right below this elite tier would fall PvZ, A4ER, Sword of Fargoal, and Zombieville
Spider: Secret of Bryce Manor. It has a cool way of unraveling the story while you go around as this charming little spider eating bugs. It was Toucharcade's Game of the Year, so give it a look. Oh yeah, and EnviroBear goes without saying.