I propose a path that anyone can take to obtain the "Alien Maggots Are Gonna Pay" achievement. The path is straightforward and does not necessitate rushing. You can learn about the route by watching the video or reading the text below. Enjoy!

1. Destroy the orange gas tanks and go down the vent.
 
 
2. After you land, look to the right. You will see an alien standing on a box and the sign "Innocent?". You have to get to the sign. To do so, kill the alien and jump on the box. From there, jump on the ledge. From the ledge, jump towards the sign.
 
 
3. Under the sign a platform with a rocket launcher will rise. Take the rocket launcher.
 
 
4. Head right, to the cinema. A cracked wall can be found within the cinema's ticket booth. Fire a rocket at the wall through the ticket booth window.
 
 
5. Walk through the destroyed wall and step through the doorway on the right.

  
6. Open the door ahead.
 
 
7. Walk straight through the hallway.
 
 
8. Open the door at the end, on your right.
 
 
9. Walk through the door and go up the stairs to the director's booth.
 
 
10. (Optional) If you're out of rockets, hop on the movie projector. A hidden wall will open, with aliens and rocket ammo behind it.
 
 
11. Walk to the small window.
 
 
12. Break the glass and pull the lever next to it. A movie screen will appear from behind the theatre curtains.
 
 
13. Shoot the crack in the middle of the movie screen.
 
 
14. Jump through the window, jump through the hole in the screen and turn left. Kill the alien on your way and pick up the jet pack.
 
 
 
15. Turn around and jump through the window.
 
 
16. Look left and up. You will spot a bridge. Use jet pack to fly to the bridge (press "j" to activate the jet pack with default settings).
 
 
17. On the bridge, look left. You will see the end of the level "self-destruct button". Walk to and press it.
 
 
18. Congratulations! Unless you went away from your PC to attend other things during the completion of this route, you have most likely beat the level under 3 minutes.