Your escape pod lands in the middle of an alien bathhouse where lots of naked alien women are lounging. As you land, they scream and swim away. Guards rush in. Run out of the bathhouse and to the right. As you come onto the bridge leading away, guards approach from the right. Use the shield-super-blast-fire technique to kill the guards. There will be at least four guards. When no more guards approach, run to the right and keep going. In the next area, your friend breaks through a stained glass window and starts running beside you. Keep going right. In the next area, your friend is a few steps ahead of you when a blast from the foreground takes out the floor beneath you.
Jumping won't help. You fall from the bridge as your friend looks around in confusion. As you fall, an arm reaches out to grab you, pulling you up onto a lower ledge. This alien is a real meanie (you can tell by his red eyes). The bad alien slams you against the wall and then punts you off to the right. As he walks towards you, he doesn't see your friend drop down onto the ledge behind him. Start crawling to the right and keep crawling. Behind you, your friend gets the jump on the bad alien and they start fighting. Crawl, crawl like you've never crawled before, to the set of levers on the right side. Soon, the bad alien throws your friend over the ledge and starts towards you.
Below, your friend hangs onto the ledge by his fingertips. As the bad alien reaches the middle of the purple thing on the left, use the fire button or space bar to pull that lever. A huge super-super-blast zaps the bad alien into charcoal. Now pull another lever, opening the super-teleporter above you and immediately start crawling left. Don't stop crawling because the guards are catching up. The first two shots will miss you but, if you stop, the third shot will kill you. When you crawl under the teleporter, you'll be transported up to the roof. Congratulations. You've won the game. Now sit back and watch the closing film.