The Grim Adventures of Billy and Mandy is a 3D fighting game based on the Cartoon Network animated series of the same name. Borrowing heavily from games like Power Stone, Billy and Mandy features frantic, often chaotic gameplay that's surprisingly fun for the first few hours. It doesn't take long to unlock all of the characters, stages, and game modes, though, and once you've done that you'll have a hard time feeling compelled to keep playing the game.
The gameplay in Billy and Mandy is simple. You choose one of the 15 playable characters and beat the living crap out of up to three other characters at a time. You have anywhere from one to four lives going into battle, and when you lose all of your lives you're out of the match. Each character has a weak attack and a slower, harder-to-pull-off strong attack. In addition, each character has a couple of special "mojo" attacks. As you fight you'll find and collect mojo balls, which fill up your mojo meter. Once it's full, you can perform a mojo smackdown, which is a series of attacks that automatically hit for heavy damage. If you fill up your mojo meter two times over, you can do a mojo meltdown attack. When you pull off a mojo meltdown the camera will zoom in on the action and a series of button icons will appear on the screen. If you press the corresponding buttons in time, you'll instantly kill your opponent. If you're playing the Wii version of the game, instead of pressing buttons you have to aim the Wii Remote at targets that randomly appear onscreen.
The combat isn't limited to simple melee exchanges and special attacks, though. Each stage is filled with items that you can pick up and throw, such as pumpkins, stones, basketballs, barbecue grills, and so on. There are also treasure chests scattered about that contain all kinds of weapons that you can pick up and use. There are ranged weapons such as the pane-o-glass gun, which (appropriately) fires panes of glass, a worm gun that shoots exploding grubs, and a laser-shooting scythe. There are also melee weapons like swords, hammers, and clubs. But wait, that's not all; there are also various traps and mounted weapons in each stage, so you can wait for your enemy to walk on a specific part of the floor before hitting a switch to make the floor electrified. Or, you can hop in a giant ballista and start shooting down your enemies from afar. All of the props in each level give you plenty of ways to go about beating up your enemies, and when you're playing with four players the action can get chaotic, which makes it difficult to tell what's actually going on at times.
All of the standard game modes are accounted for in Billy and Mandy. There's an extremely brief story mode that takes you through about half a dozen stages to face a weak boss. It only takes about 20 minutes to finish the story mode, so once you've played through it a number of times to unlock secret characters, outfits, and video clips, there's no reason to go back. You can also unlock all that stuff by completing the 45 missions in the game. The missions are all just battles with special objectives, such as to smash as many pumpkins as you can within three minutes. The missions are fun ways to unlock new characters, but they aren't especially difficult, and you'll probably be able to beat them all within a few hours.