Alien Soldier: Stage 24
3Epsilon-Eagle take an elevator to the core to the space station he entered. You can move the elevator up and down on your own.
The only thing you do in Stage 24 is fight a boss, who is a security system that attacks with lasers, missiles and itself. It's weakspot is right in the middle.
When it's at the bottom of the screen, it tries to hurt Epsilon with the explosions of its missiles from below. When it's on the top of the screen, it drops electrical bars on you. You can destroy these bars.
When it turns red, it becomes invincible and switches its spot. Dodge all of its parts as they move along.
Really, dodge everything else and keep shooting at the core when its safe, and this boss will go down quickly, taking you to the final level of this whole game.