The Mental Institution is the final boss of Serious Sam 2.


The Mental Institution is Mental's home, and also has a spaceship for an escape emergency (such as Sam's arrival there). When Sam defeats all the enemies around the Institution, it will activate its wheels and start moving towards Sam.


The Mental Institution has a vast arsenal of weapons: Fireball Launchers, Cannons, Rocket Launchers, and can spawn a mass force of planes. Going near the Institution's wheels will result into them crushing you.

Its first attack are three waves of modified Fatso Fighters. These will crash into the player.

Its second attack is Fireball Launchers.

Third attack consists of three waves of modified Seagull Fighters. Unlike the regular counterparts, each one can log much larger amount of bombs than the regular fighter, making it nearly impossible to dodge completely.

The fourth attack consists of shooting cannonballs at the player.

The fifth attack consists of three waves of regular Fatso Fighters.

The sixth attack consists of firing a large amounts of missiles.

After that attack, the core stays exposed until the end of the fight. When not finishing the boss quickly, it will roll over the player.


  • The fight itself is pretty straightforward, just rush backwards and shoot any projectile or enemy it spawns, grab the Repair power-ups to survive and attack it when its core is exposed, especially if you have Serious Damage. Albeit having 1 million HP, it is dealt A LOT of damage when shot at the core. If Sam's vehicle is destroyed, Sam dies.
  • The most important thing to take care of first, as said above, is the Fatso Fighters spawned by it, as they will deal tons of damage if they get you with their lasers and then crash on you, so take them out as soon as possible. Seagull Fighters are also a threat, but shooting the core is a higher priority rather than shooting them. Of course, if you can dodge the Fatso Fighters, while the core is open, you can just shoot it and evade them.
  • Usually, the boss should be done for during the cannonball phase without Serious Damage or fireball phase when Serious Damage was grabbed.


  • Appearently, there are other residents living in the Mental Institution aside from Mental. The other residents are, as seen in the cutscene when you finish the Mental Institution level: "Napier", "Luthor", "Moreau", "O.J.", "Vader", and of course Mental himself.
  • The Mental Institution has the most HP that any enemy or boss in the series (along with Kwongo).
  • The battle with the Mental Institution happens only in the PC version of the game. It was added in the game in its last months during the development cycle.
    • In the original trailer for Serious Sam II, two Ugh-Zans can be spotted walking towards the player. Why they were cut from the game is a mystery.
  • Upon beating the boss, a cutscene is cued. Sam presses Mental's name on the residence list, but when the camera angle changes, he seems to be pressing a different button.