If you're looking for a deep ruleset, take a look at Oktoberfest. 14 modes, 2 primary multiballs, 4 mini-wiz modes, and other features give the game lots of breadth. Then there are 14 steins, each of which give two unique power-ups, and you can mix-and-match them in almost unrestricted combinations, giving the game unprecedented depth. Most importantly, the game is just a lot of fun!