Saturn: Tunnel B1

You are on a mission to destroy the ultimate weapon of your enemy. This involves travelling through a set of precarious tunnels in your high-tech hover-craft. The tunnels are filled with enemy vehicles, choppers and sentry guns which you have to take out or avoid. To make life even worse, a lot of sections require you to clear them in a given time limit. The only good thing is that you'll be able to upgrade your weaponry often.