The gameplay mechanics of MegaMari are based around the Mega Man series, primarily Mega Man 2. Marisa, accompanied by Alice, battles through eight stages in any order, fighting a boss at the end of each stage, before moving on to Patchouli's multi-stage fortress for a showdown with the sorceress herself.
Marisa and Alice behave exactly like Mega Man in Mega Man 2, from their running speed and jumps to the knockback when they are hit. Both girls handle exactly the same, with one exception: their shots. Marisa fires pellet-shaped magic bursts like Megaman's pre-Mega Buster arm cannon, while Alice shoots a laser beam. Marisa's shots are twice as strong as Alice's and can destroy most weak enemies in a single shot, making her good for dealing with swarms of enemies, but Alice's can autofire continuously and penetrates some enemies' shields, making her a good choice to battle some enemies with unconventional fighting styles, such as the Prismriver Sisters. Alice's laser does more damage at point blank range and she is slightly taller than Marisa, making it possible for her to hit some enemies that Marisa would have to jump for.
Similar to X3, X7 and X8, the player can switch between either girl at any time in the current stage (except for the third stage of Patchouli's castle). The girls each have their own lifebar, effectively giving the player two 'lives' for each life in reserve, so switching between them to spread damage around evenly helps to make it through stages, especially in the early going when the girls lack special weapons to help them out. Unlike Mega Man, the girls have shrunken, Touhou-style hitboxes, and enemy shots fired at their heads will pass right through them without damaging them-- it takes a hit to the torso or legs to damage them. This makes it possible to 'graze' enemy projectiles just like in the danmaku games, although no point bonus is awarded since the game does not keep score. As in the Mega Man games, falling on spikes is instant death, unless it happens while the girls are invincible after being hit.
Acquiring Weapons And Items
Like the Mega Man games, the girls earn weapons from defeated bosses; however, unlike Mega Man, the girls must split the weapons--upon defeating a boss, the boss drops an orb containing her weapon, and whichever girl picks up the orb gets the weapon. As a result, one of two possible unique weapons can be gained from a defeated boss, and one weapon is usually more useful than the other. This means the player must act strategically in deciding how to divide the weaponry between the girls to make them both as effective as possible. It is crucial that both girls be armed properly as they become separated from each other in the third Patchouli stage, and their acquired weapons become integral to their survival.
In addition to their acquired weapons, each girl can earn a special item. After beating four bosses with either character, Marisa will receive the Super Broom, which functions like Mega Man 2's Item-2, providing her with a long-distance air ride. Alice can also gain the ability to use her Shanghai Doll as a weapon; however, in order to unlock Shanghai, Alice must have at least four boss weapons. In other words, Marisa will receive the Super Broom no matter what (as it is impossible to complete the game without it), but Alice will not acquire Shanghai if she received three or less boss weapons. Shanghai functions like Mega Man 5's Beat, automatically homing on and attacking enemies.
Like Mega Man, Alice and Marisa can gain power-ups during the course of a stage. Yellow mushrooms restore life (small = 2 life-bar units, large = 10 life-bar units) and blue crystals recharge magical energy (small = 2 units, large = 10 units) for special weapons, giving the girls more ammo. Other power-ups include extra lives (flashing Marisa face) and three different energy tanks; a Mushroom Tank that restores one girl's life completely, a Star Tank that restores all special weapons' energy at once, and the Mega Tank, which completely restores both girls' life and restocks all their weapons. These are similar to the E-Tanks, W-Tanks and S-Tanks. Up to four tanks total can be carried at any one time; the maximum possible number of lives in reserve is six.