Quake II

This solition only for PC players.
You can use console commands for faster completion

For this achievement do next:
1) Use console (~)
2) type console command - map base2
3) turn on - noclip
4) turn on - god
5) Find exit button on elevetor
6) turn off - noclip
7) Press exit button

This achievement and the 6 or 7 following it are for beating each consecutive level of the first game. As in the first option in Level Select, Quake II.

Here are some tips for PC players only:
use ~
godmode - god (invulnerable)
noclip - noclip (fly through walls)
notarget - notarget (enemies can't see you)

No matter what the mission objective is, the mission will end once you find the exit door. I flew around each mission until I found it. Sometimes the exit door is in the next or subsequent zone. In this case you find the next instance door instead and go through that. Then continue until you find the exit door. You must turn off noclip before you can enter any door that loads the next area/ends the level.

That's what I did I just winged it. Don't take it out on me, the all Spanish video guide made me irrationally angry so I wanted to summarize my 1-2 hour completion.

This solition only for PC players.
You can use console commands for faster completion

For this achievement do next:
1) Use console (~)
2) type console command - map base2
3) turn on - noclip
4) turn on - god
5) Find exit button on elevetor
6) turn off - noclip
7) Press exit button

A cheesy method to get this cheevo and all the others. Load in go to multiplayer, press continue, local, change settings, select said level and set game mode to cooperative, difficulty easy enable max lives, instant weapon swap and infinite Ammo. Now complete the level and use lb to know where to go as this is a waypoint. Hope this helps !