Sinclair's new baby, the Spectrum, is fast getting a library of software all for itself.

The latest addition is the Spectral Invaders cassette - a faithful copy of the now veteran forerunner of the video game boom.

It is written in machine code and makes full use of the Spectrum's graphics capability.

The game is controlled by joysticks and has a high score feature, as well as the usual invader antics.

It runs on the standard Spectrum and comes from Bug Byte of Liverpool priced at £5.00 including postage, packing and VAT.

LET'S HUNT THE INVADERS

INVADERS FOR THE SPECTRUM

As the race continues among software houses to produce games for the Sinclair Spectrum we decided to test the three Space Invader games that have so far been produced for this fledgling machine.

Spectral Invaders was the first game on the market for the Spectrum and marked another first for the Liverpool firm Bug Byte.

The game is a fairly authentic version of the arcade classic. It loaded without difficulty and started according the instructions.

The main drawbacks were that the gun turret responded slowly to the keys and did not explode until a split second after it had been hit, continuing to move right or left. The missiles were also slow movers - jerking awkwardly skywards.

The Invaders themselves did not explode immediately they had been hit either - causing you to hesitate, unsure if you had hit them or not.

On the plus side Spectral Invaders was the only game of the three we looked at that offered a two player game. It had the fastest and most authentic mystery flying saucers, it also had the best score board, flashing to indicate player one or two.

Despite its faults, Spectral Invaders was the only version that looked and felt at all similar to arcade Space Invaders.

Psion Software - the official Sinclair software writers - entered the field with Space Raiders, the slowest version we tested.

The Invaders don't move down the screen in vertical columns in this version making them particularly easy to hit. Their side-stepping motion means that the gaps between the columns are blocked so you can hardly fail to hit something once you get a missile in the air.

The mystery flying saucers didn't look too much like flying saucers and moved so slowly they could be picked off with ease.

About the only department in which the Psion game beat the other two versions was sound. The Spectrum produced clear well synchronised bleeps as the ships exploded.

Space Raiders loaded well - the Psion logo appearing seconds after the play button on tape was depressed - cutting out some of the nail-biting I experienced with other Spectrum games.

Southampton firm Quicksilva were hot on the heels of Bug Byte with their version of Invaders for the Spectrum - Space Intruders.

This was the fastest of the three games. So fast in fact that it detracted from the playability of the game. Not because it made it impossibly difficult, but because you had such a speed advantage over the advancing fleet that you could shoot them down with ease.

The missiles could be fired far too fast and furiously. You could kill a whole column of Invaders in a split second, sometimes without dodging right or left, which in turn made the fleet relatively easy to defeat.

In fairness to Quicksilva their version does have a number of features which the others do not.

Most useful of these is a hold button which enables you to answer the phone or make a cup of tea and then continue where you left off when you are ready. It also has a high score facility which enables you to enter the top ten high scores of the session with the initials of the players.

Space Intruders displays clear instructions on the screen and also gives you the value of the various Invaders. Extra features are, however, no substitute for a good playable game, which I do not feel this version from Quicksilva gives you.

For my £5 Bug Byte offers the best game of Space Invaders on the Spectrum so far.

Both Bug-Byte's Spectral Invaders and Quicksilva's Space Invaders approach the standard of real arcade games. Spectral Invaders is almost an exact copy of Space Invaders, complete with four different colours for invaders, a flying saucer and high score. Some effects are slightly slower than the Atari original but the graphics quality and the use of colour and sound is excellent. Quicksilva's Space Intruders also had a mutant invader that wobbled and was worth extra points and a hold facility to allow you to stop the game at any point.

ARCADES BROUGHT INTO THE HOME

John Gilbert reviews more complex games.

Almost every major type of arcade game has been simulated on Sinclair computers. There are also new games which have an arcade format but have evolved on a microcomputer. The Spectrum is an ideal machine on which to play arcade games. The quality of them has improved substantially since the launch of the machine. Some of the first arcade games to be produced for the Spectrum were versions of Space Invaders, the game which started the arcade craze.

Spectral Invaders was the first to be announced by Bug-Byte, which was already renowned for its arcade and adventure games on the ZX-81. So far it is the game which most closely resembles the original arcade version. Although it is slow it is difficult to score points, as you can fire only one laser blast at a time.

Another invaders game, Space Intruders, was launched at about the same time as Spectral Invaders. The game is much faster and is recommended for those who like to keep their fingers on the fire button and amass a big score. The only criticism is that the aliens and mothercraft are very small and the mothership is blue on a black background and so is very difficult to hit. Apart from that Space Intruders from Quicksilva is good value at £5.95.

Namtir Raiders, for the ZX-81, is a space invaders game with a difference from Artic Computing. The player still has to face the hordes of aliens which come down the screen but the laser base can be moved up and down as well as left and right.

The player has five laser bases during the game and they can take only five hits from alien bombs. There are three levels of difficulty-easy to impossible. The game, costing £3.95, is addictive and the graphics are neither awkward in design nor jerky in movement.

The game which is gaining popularity with 48K Spectrum owners is Time Gate, from Quicksilva. The authors claim that it is the ultimate in 3D arcade space action. The game is loaded in two parts, the first being a lengthy instruction manual. After the manual has finished you can load the game. The object is to destroy a race of aliens called the Squarm who are trying to colonise Earth. The enemy fighters are also seen in 3D and so are the planets on which the player can land to refuel and repair the ship. It is by far the best arcade action game so far for the Spectrum and costs only £6.95.

Asteroids is also becoming popular on Sinclair machines. One of the first companies to launch a version for the ZX-81 was Quicksilva. It was a good version on such a small machine and is still proving popular.

Quicksilva has also introduced a Spectrum version called Meteor Storm. It has the added attraction of speech before play. It is difficult to hear the words but we are informed by the authors that it says "Meteor Alert... Meteor Alert...". Meteor Storm is a novel version of Asteroids and costs £5.95.

Sinclair Research has a good game of asteroids, called Planetoids, in its new Spectrum Software library. The asteroids are in 3D and much careful design work on both the asteroids and the player's ship seems to have gone into the game. Planetoids costs £5.95.

Artic Computing seems to be the only company to have produced a version of Galaxians for the ZX-81. ZX-Galaxians looks like Space Invaders but the invaders are 'V'-shaped and are supposed to be inter-galactic birds. The birds swoop from formation and bomb the player's laser base. ZX-Galaxian is slow in action but can still be a very addictive game. It costs £4.95.

Defender is still a much-sought-after game in the arcades and Artic Computing took advantage of that early by producing a version for the ZX-81. The graphics are not particularly interesting and the spaceship which the player flies across the landscape is made up of a series of blocks which look only slightly like a ship.

Despite those criticisms, the original idea behind the game is still there and the Artic version can be exciting, as you see the enemy ships rushing at you from the other side of the screen.

With the arrival of the Spectrum, many manufacturers found an interest in the arcade game Scramble. The best and fastest version so far is from Mikro-Gen. In the game you have to go through caves which become smaller and smaller as it progresses.

The game becomes progressively more difficult and can be run in slow, normal and fast modes. It costs £3.95.

Silversoft has a Scramble-type game called Ground Attack. It works on the same principles as the Mikro-Gen game but is much slower. There is a good deal of blank screen between game rounds and the average waiting time between rounds is 15 seconds. Ground Attack costs £5.95.

The range of arcade-type games on Sinclair machines is always increasing. Manufacturers seem to feel safe in producing standard arcade games such as Space Invaders and Scramble. Those games, especially for the Spectrum, are becoming more imaginative and the graphics and sound more impressive.

Manufacturers have to be careful about copying ideas from other games but with the imagination of some of the firms in the Sinclair market, children and many adults will be kept happy with arcade-type games on the ZX-81 and Spectrum for a long time.

Space Invaders games have now been overtaken by Pacman in popularity.

Bug-Byte, 98-100 The Albany, Old Hall Street, Liverpool L3 9EP.

Quicksilva, 92 Northam Road, Southampton SO2 0PB.

Artic Computing, 396 James Reckitt Avenue, Hull, North Humberside.

Sinclair Research, Stanhope Road, Camberley, Surrey GU15 3PS.

Mikro-Gen, 24 Agar Crescent, Bracknell, Berkshire RG12 2BK.

Silversoft, 20 Orange Street, London WC2H 7ED.