You need balls to play Ballz.
Like the game title claims it be, Ballz is a full 3D fighter on consoles that were known for 2D games. You'll beat up your opponent's - balls - as you run around a 3D field while a scoreboard in the backdrop wisecracks you every step of the way. Like any fighting game out there in the history of history of fighting games you can pretty much button mash your opponent to oblivion, or take the strategic route and knock his - balls - out with each character's unique set list of special moves.
And when I mean "unique" I really mean it in every sense of the word. Ballz 3D's character roster is full of oddballs: Boomer the clown attacks player's with his irritatingly quick and unpredictable attacks; Yoko the monkey "farts" at you (I'm not kidding); and Kronk uses his club as if it were made for golf...and your head as if it were a golf ball. The game has a nice way of balancing out the characters too: the big boys, for example, have more HP than the small characters but are much slower, while the small characters can dish out a load of attacks but take more damage.
Ballz 3D offers both a 1-player mode and 2-player mode with a friend, and even features on-line play for the Genesis version if both of you have an Edge 16 modem, which connects to your phone line. Don't think for a minute that 1-player mode is lacking though: this mode has you beating a gauntlet of fighters from the game as you gain new belt colors on the way to beat the game's final boss, Jester. Before earning your new belt color you'll have to beat the merciless bosses of each round that range from an ostrich to a T-Rex. They're no pushovers either as button mashing will only get you hung up in they're counter attacks (and believe me that you don't want to get hit by those). 1-player mode is a nice challenge for those that want more out of the game.
Unfortunately, 1-player mode suffers from nasty computer opponents, who spam - a lot. Spamming is common practice in almost every instance, heck, either you spam or they'll spam you - to DEATH. You can basically use a "Spanking" move (yes, I'm not making this up) over and over until the opponent either explodes or escapes. This attack does A LOT of damage if it's continued too far, and note that your opponent can use it too. Other cheap moves include Turbo's "Super Blow" move which the COMP uses way too much and is a pain in the arse to avoid; and Crusher can practically kill you in one hit with certain moves.
If you're up to the challenge and want a unique, goofy fighting game experience, then you can do far worse than Ballz 3D. 2-player mode is obnoxious fun, the sound affects are in-your-face, and come on, the back of the case says "It's the coolest *!#!@*#! fighting game on the shelf"! So go on, kick some balls!