The player's first encounter with Rootmars is in a small room full of wired tentacles. The room lights up to reveal the Martian leader ready to fight. Rootmars attacks by producing energy balls from its dome and launching it towards the player. The first energy ball takes a few seconds to launch; each subsequent energy ball is periodical.
Rootmars at first fires smaller energy balls that launch at fast speeds. Once its damaged enough, it'll produce larger energy balls that fly slower and take a while to disperse on the ground. At near death, Rootmars produces larger energy balls at a faster pace. Occasionally, an energy ball produces a Heavy Machine Gun, Rocket Launcher, or Laser Gun crate when it hits the floor.
The Rugname begins to self-destruct once Rootmars' dome is shattered. When the heroes exit the exploding spaceship, the heavily damaged Rootmars flies in, grabs the SV-001s they are residing in, and begins its final attack.
In Other Games
Fake Rootmars is a stage boss. Similar to the Tetsuyuki, Fake Rootmars is a stationary unit placed exactly like its arcade counterpart. Fake Rootmars attacks by launching a small energy ball and then two large energy balls. Its weakpoint is its dome, so any units without anti-aerial attacks will walk from base to under Fake Rootmars and stay still.
Fake Rootmars is again a stage boss, now serving as the Sunday Boss in the Attack! mode. The fight functions the same as in Metal Slug Defense.
In cutscenes, Fake Rootmars represents the real Rootmars whenever the latter is speaking.
The Mars People Officer and the Chief Operating Officer can summon Fake Rootmars through a portal and have it launch energy balls that home on the nearest unit and stun them. The COO's Fake Rootmars' energy balls can also eliminate projectiles.
- Early concept art implied that Fake Rootmars and True Rootmars were the same person (due to the concept art depiciting True Rootmars with mutilated tentacles and loose cables, along with his clawed arms), however, in Metal Slug Attack, it was revealed that Fake Rootmars was a separate character.