Your task is to defend your castle against the evil marauders who are climbing the walls. To stop them you must hurl rocks. But naturally they get annoyed at this and start to move even faster.

Stop them reaching the top of the wall at all costs or you've lost.

There's a choice of joystick or keyboard operation. But using the keyboard is just too fiddly when you must more fast. I was only happy when using the joystick.

Siege is a good example of not always choosing higher-priced and better advenised games. At £6.99 this game is very good value from one of the lesser-known software houses.

If Space Invaders becomes a little too predictable, try Siege instead.