This program comes from the author of the block-busting ZX81 games 3D Monster Maze and Defender, and this quality is reflected in 3D Tunnel. To set the scene: you are in a long winding tunnel infested by bats, rats and spiders, and even a London underground train (48K version only). As you move down the tunnel at one of the selected speeds, you can see a cross in the centre of the screen. It is possible to change your relationship to the tunnel via a joystick or various sets of keys on the keyboard. The idea of the game is to get to the other end of the tunnel by killing off or avoiding the strange creatures, as well as trying to keep within the tunnel.
The instructions are good though a little more about the different key configurations would have helped. The initial keyboard layout is very awkward as it seems to think that you are better at imagining a joystick than seeing your fingers on the keys.
The game itself is a breath of fresh air to me; it is not based around space, is original, and uses the graphics capabilities of the Spectrum to the full. The detail of the bats, rats and frogs which come at you is incredible - it is hard to believe that it is a Spectrum being used. If you have a 48K machine, you also have the task of having to avoid a London Underground train - the graphics are amazing.
There are three levels of play, from slow to fast, and the option of demonstration and practice runs at particular waves of attackers. The graphics are so good that I could have just sat and watched the demo for an hour. This is very professionally put together and a game that I would recommend to anyone.