In Airlock your objective is to escape from a crippled submarine before it sinks deep into the ocean. Level by level you have to retrieve the hatch keys and get out before the compartment floods. Run and jump to collect the keys and to avoid the torpedoes which have shaken loose. If one hits you you will be temporarily stunned. Time is very important as you don't have much. On the positive side, any unused time at one level will be credited to the next.