Sixteen scientists are trying to colonise planet XA2 but dastardly alien craft are bent on enslaving them. You have to protect the hapless Earthings by blasting the enemy from the skies.

The aliens appear as yellow blobs which get larger as they approach you and shift one square at a time up the screen.

When the ships are large enough, they can send teleport beams down to the planet surface to pick up the scientists. To prevent this happening you have a crosswire which destroys the ships when aligned with them.

There are 32 aliens to be disposed of and they appear across four screens along with red deflector shields. If you hit one of these you are disabled for several seconds and more people will be lost.

The four screens can be traversed by a nifty little scroll routine which does the unexpanded Vic proud. By holding down 'fire' and moving left or right you can scroll to a different section of the planet.

To help you pinpoint where the aliens and humans are there are eight indicators at the top of the screen, four green ones showing the numbers of aliens in the four sections and four blue ones showing the scientists' locations.

Good defenders can get large bonus scores for each scientist left on the planet and will move on to protect another batch.

But if all of your people are captured, you'll be left with an unpopulated planet and a lot of explaining to do back home.

The action is a bit static except for the excellent scrolling and as with many unexpanded games has trouble providing much lasting interest despite its clever conception as a game.

The game concept is uninspiring to say the least - flying a cross into yellow blobs is not going to set most people's pulses racing.

The game is not bad considering it's on the expanded machine but it is very unrewarding to play since collisions are against my video-gaming nature.

The surface display is good with some clever detail on it of bases and towers and the scrolling screen is nice and smooth.

It's all rather simple though and won't interest anyone for long.

This is a very lacklustre version of Defender. Instead of firing at the aliens, you just have to bump into them. You are supposed to protect the scientists who are preparing the planet for colonization.

The graphics are a mixture of small uninteresting aliens and large, block-like buildings.

Sound is very basic and consists of a piece of uninspiring music and a few shots of white noise.

It's a terrible game. How did they do it?