1-4 players (Defaults on 2 players in MAME. Has 3 4 player possibilities: 2 coin slots, which forces a character on each Start button; 2 cabinets combined, which forces characters to the Start button, and has 1 & 2 player sharing a coin slot, and 3 & 4 player sharing the other; and 4 coin slots, which is the Konami style of each character forced onto a specific coin slot/Start button. The 2 player version allows players to choose their character.)
Hanzo(blue, water magic, wields a katana), Sasuke(yellow, wind magic, wields a kusari & kama[chain and sickle]), Akane(red, fire magic, throws shuriken), Genta(green, Earth magic, wields a sansetsukon[3 piece staff], pictured above)
Button 1: Attack
Button 2: Jump
2, 1 Jump attack
1+2: Ninja spell(requires a scroll)
Left, Left/Right, Right: Dash (can be used as an attack, Hanzo's especially)
Up, Up/Down, Down: Vertical escape (so it wasn't a Streets of Rage 3 original after all... This can also be used as an attack)
Your character collects items by walking into them. After your first set of lives you'll continue with a scroll. Like Golden Axe, the more scrolls you collect, the more powerful the ninja spell your character pulls off. If you don't use your scrolls before you lose the last life of a given credit, or before a stage ends, you'll lose them. Your characters can hold more than 4(it becomes a number at that point), but can only use up to a level 4 spell. Basically use the scrolls as you need them. The jump has considerable reach, and can move far, even diagonally, across the screen.
Attack objects(use jumps for tall objects) to break them, or walk by doors to open them, and possibly get some items. Aside from scrolls, there are these orange star items that create an energy field that attacks outwardly for a while, but it doesn't keep your character safe, so still be wary of letting enemies get in close. There are also health restoration(food) and invincibility(green jewel/orb) items. One item makes you invincible while you can damage enemies by dashing about the screen, which looks like a typical ninja speed icon in video games. A clock freezes enemies in time.
Some stages have wall scaling sections, where your character can no longer jump. They can still use a ninja spell however. Sometimes there are traps your character can interact with, or step on, that hopefully hit a bunch of your enemies. Sometimes, like in parts of stages 3 & 5, it's just better to move on than to stick around and fight an unending horde of enemies.
Akane's range does seem to give him an advantage over the others, it even extends to his jump attack. Genta seems to attack faster than the others. If Hanzo and Sasuke have any advantages, they're not as immediately noticeable. I would advise taking advantage of the full extent of your characters weapons range, and try not to let enemies get too close.
The art style is fairly odd, and cartoon-ish. In spite of that, some enemies die in pretty gruesome ways. No blood shown or anything, but some may be ripped in half, or literally fall to pieces.
For the most part, you're likely to be mashing 1 over and over again, or using the jump attack to hit flying enemies. The game gets by on the gimmick of the item power-ups. Fun, but once again, on the simpler side, in spite of slightly more advanced mechanics.