Enemies.

The enemies appearing at all levels. They can be different. Plasma Cannon enemies, Rocket Launcher enemies, etc. Warning: This page can has spoilers.

Plasma gun enemy:
The plasma gun enemy is the first enemy and it has Plasma Gun.

Light Plasma Machine-Gun enemy:
The enemy has the worst hp, but nice speed and Light Plasma Machine-Gun.

Plasma cannon enemy:
The enemy looks like Plasma gun enemy, but has Plasma Cannon.

Grenade launcher enemy:
The enemy is same like Plasma gun and Plasma cannon enemies, but it has grenade launcher.

Rocket launcher enemy:
The enemy has Rocket Launcher.

Laser sword enemy:
The laser sword enemy has laser sword.

Large Rocket launcher enemy:
The enemy is larger and more armored than Rocket launcher enemy.

Heavy Plasma cannon enemy:
The enemy has Heavy Plasma Cannon, and larger and more armored than Plasma cannon enemy.

Plasma Machine-Gun enemy:
The enemy has Plasma Machine-Gun.

Secret weapon enemy:
The enemy appears at level 11 and has Secret Weapon. On the level 11 are some copies of the enemy

back the gates, but they are fake (you can test it if you use Secret Weapon bug, which can shoot through walls) : when you shoot them with the Secret Weapon, lasers are coming across them.