Two teams, "light" and "dark," face off in enclosed levels, with the goal of, well, shooting each other. Before each match, each player selects a weapon from an inventory including a sword, cannon, claw, and a few others. This affects your movement speed, shot range, melee options, and power (this is also part of the single-player game). Then, each group of three attempts to deplete the other team's shared lifebar by taking down each player's individual lifebar, which depletes after maybe five hits. When one team has taken enough damage, one of its members gets a Pit icon on the top of his/her head, identifying that player as the target for the other team. Kill the other team's Pit, and you win.
My match took place across a pretty generic, grassy green area, with a few narrow paths up between different elevations. It was big enough, at least, to lose sight of the people on the opposing team from time to time. Powerups spawn at preset locations, allowing players to run and vie for the occasional grenade item, which can be thrown into crowds, or life recovery item.
Uprising's multiplayer, having the same controls and movement as the ground portions of the single player, suffers from the same issues as that component. Holding the 3DS with your left hand on the circle pad and L button (which fires), while aiming with the stylus in your right hand, is quite unwieldy, and basically only possible if you've put the 3DS on some kind of stand. I also felt that the melee attacks, which are triggered when you hit the L (shooting) button in close range, provided insufficient visual feedback, mostly because everything moves at such high speed. I didn't really know at all times whether I had connected with a melee attack or just been shot. On the other hand, the dash move is executed well and feels satisfying, allowing you to dodge shots and attacks with a flourish, reminiscent of Sin and Punishment: Star Successor.
Nintendo also showed off an AR card-based multiplayer mode, which uses new Kid Icarus
-themed AR cards to display characters fighting each other on your table or whatever. I have yet to get hands- or 3D camera-on with this mode.