The Line is a puzzler designed to put the player in constant panic. The game is like all other puzzlers but with a small extra; this small extra is a big yellow line which takes the quickest route from entrance to exit and all you have to do is stay close to the line and you should be good. However the exit is of course locked and the components to open it are scattered around these huge test chambers. You’re not really told what happens when you leave the line but get a pretty good idea at the start of the game when your neighbour is devoured by the creature stalking you called The Hunter. Fortunately you’re helped along by The Director who you only see in AI form until the end of the game. The inhabitants of the test chambers don’t seem to like the idea of you escaping and so will try to stop you.
The underground test chambers of some unknown organisation on a destroyed Earth.
There's The Director who teaches you the controls for the game and is also the only one in the game who talks. There's also the wonderful inhabitants of the chambers; Barnacles (turrets) and Watchers (ceiling mounted lasers) and there's you, the completely clueless player who has no dialogue.
The usual ways for movement left click to shoot and right click to pick up and drop.