This is a single player first-person action shooter.

Easy and uncomplicated to play. Not so much stealth and sniping but more of speed and action.
19 levels.
A relatively open world allows the player to choose any path. Shoot all enemies or just run through the level.
A mixture of realistic environment and unrealistic enemies.
The humanoid enemies are zombies and biomechanical mutants.
A large mech fires homing missiles.
Another mech is armed with machine guns.
The humanoid enemies chase the player.
All enemies explode on close contact with the player.
The biomechanical mutants shoot fireballs.
Seems to work well with linux + proton.

Alone but strong

Summary