One of the main problems with the computer games market is the vast number of companies that are trying to get in on the scene. Trying to buy a piece of software is a very risky business - all you have to go on is the blurb the manufacturer puts on the cover. All too often this means you buy what promises to be a really exciting game only to get it home and find it's extremely poor. So how can you be sure of buying a good product?

First, you can examine the charts in computer magazines. If a game gets into the charts it should be fairly goo. Secondly, read the reviews in the computer press to see what other people think about the game.

For anyone new to buying computer software, here are a few established and respected software companies.

Spectrum owners are the ones who really suffer, as there is simply so much software to choose from. The company which really set the standard for Spectrum software is Ultimate. Its first release for the 16K Spectrum took the machine to its limit. Ultimate has kept up its standard and is still launching good games.

Software Projects is another company that has produced consistently good programs; the best known being Manic Miner and Jet Set Willy.

Hewson Consultants, whose first games received some bad reviews, is now producing excellent games - Avalon definitely deserves a look.

Gargoyle Games is a new company which seems to be producing very high quality software. Tir Na Nog, an arcade adventure, is particularly impressive.

Another of the 'old boys' in the software industry is Ocean. This company is now converting a number of the top American programs into the Spectrum. Finally, Micromega consistently produces software of high quality. Its program Death Chase on the 16K Spectrum raised quite a few eyebrows when it was launched. Many shops sold out within a couple of days of receiving stock.

Commodore 64 owners are a little less fortunate when it comes to naming companies which maintain standards. Many produce a couple of top games and then let the quality fall.

Alligata produces some excellent games - Blagger, Son Of Blagger and Loco all held places in the software charts for quite a while, while one of its latest releases, Rocket Roger, should do very well. Novagen has only ever released one game, called Encounter, which was a very fast, 3D shoot-'em-up. If its next program is as good, Novagen should go a long way.

Beyond is starting to produce some very high quality programs. Psi Warrior, although difficult to play, has some attractive graphics.

Most of the really good C64 software is imported from the US, and a number of companies have been set up to produce American software under licence in Great Britain.

US Gold, CBS and Ariolasoft all have some exceptional titles.

There aren't as many games around for the BBC as other machines but there are still a few notable companies. Acornsoft produces some good software and not just good games. Elite shot straight to the top of the charts when launched. Alligata also publishes excellent BBC games.

Micro Power is another company which produces software for the BBC. Although not all of its titles are brilliant, most are well worth a look.

Many games are so similar to one another that it's often very difficult to distinguish between them. Here's a run-down of just some of the 'types'.

Spectrum owners looking for a platform game could do worse than buy a copy of Software Projects' Manic Miner. This is the one that started the flood of so-called platform games. The aim is to guide miner Willy through numerous caverns, collecting all the objects while avoiding the monsters and collapsing floors that are scattered around - Jet Set Willy, the sequel to Manic Miner, proved to be as popular as its predecessor. In JSW you don't have to collect all the objects before moving onto the next room, but all of them must be collected before you can finish.

Commodore owners are lucky, Software Projects has converted both games to the C64. No attempt has been made to use the additional facilities of the C64 and the games look identical to their Spectrum parents.

Alligata Software has produced numerous platform games for the C64; its first being Blagger. More use is made of the machine in this game with larger graphics than the Software Projects' games. Son Of Blagger is the follow-up to Blagger and a new idea was introduces here. Instead of your man moving around, the rooms scroll smoothly past in eight directions.

Alligata also caters for BBC owners, and both these games have been converted for this machine - and extremely well. In fact, they have more screens than any other BBC platform game.

For those of you with tendencies to spend time in the arcades, there are plenty of programs which have been converted onto home micros. Versions of Defender are available for most machines. Design Design calls its version Invasion Of The Body Snatchers. This is an extremely fast game and will challenge even the most hardened arcade player. Acornsoft's Planetoid is very similar to the arcade version, as the graphics and sound have been superbly done. Alligata's version for the C64 is rumoured to be so close to the original that if you know the tricks in the arcade game you can use them to advantage here.

Followers of Scramble are catered for with Cavern Fighter from C Tech, and Penetrator from Melbourne House. The Melbourne House version was one of the first games to become available on the Spectrum. Even so, it remains extremely popular. Cavern Fighter has larger graphics than the version from Melbourne House and offers an extremely challenging game. Acornsoft comes to the rescue for owners of the BBC with Rocket Raid.

This is near identical to the version in the arcades and is probably slightly faster, making it a tough one to play. Anirog produces a competent version for the C64 called Skramble, but there are others. Pacman started the maze game craze but is one game that hasn't translated well onto micros. Acornsoft's Snapper for the BBC is probably the best version available for any micro. Atarisoft (the game originates from Atari) has launched a Spectrum version that strongly resembles the arcade game. It's fun to play, but lacks the polish of its parent. Mr. Chip produces a version of Pacman on the C64 called Pacmania, but again there are many others.

Guzzler on the C64 from Interceptor Micros is a prime example of how the Pacman idea has been adapted. In this guide you must dash around a maze eating fruit from food stores. Once you've eaten fruit, you become rather fat and have to meet up with Denis the Deflator before you can carry on with playing the game.

Most of the popular arcade games that are converted for micros come from the US and so are available on the Commodore 64 long before any other micro. Up and Down, Star Wars, Buck Rogers and Zaxxon are all extremely popular in the arcades and extremely good versions are available on the C64.

Obviously not all arcade-type games are clones of arcade originals. One very good example is the latest release from Microsphere, called Skooldaze. In this you play the part of a schoolboy who is trying to get his school report before it's seen by the headmaster. Probably one of the funniest games this year, and a real treat for Spectrum owners.

A new type of arcade game that is only just starting to appear is the arcade adventure. The goal in these is to complete a set task, exactly the same as in a more traditional text adventure, except that the description of a traditional adventure is put into picture form. Your character can run around rooms collecting obnjects and fighting monsters, all under keyboard or joystick control.

Ultimate's latest, Knight Lore, takes the Spectrum to its limit, with rooms pictures in true 3D perspective and extremely smooth animation.

Ant Attack from Quicksilva is available on both the Commodore 64 and the Spectrum. In this arcade adventure you find yourself in a town which is depicted in beautiful 3D. The aim of the game is to rescue the girl or boy who has been trapped by the giant ants which roam the city.

Quo Vadis is one of the few arcade adventures available on the C64 and is supposed to have more screens that any other.

Simulations are another type of very popular game and a particularly varied selection of offerings is available. Best without doubt is the excellent Flight Simulator II on the Commodore 64. The only problem is that it weights in at a pricey £40. Acornsoft, as usual, does a superb Spitfire simulation on the BBC - Aviator. Spectrum owners are catered for by Fighter Pilot from Digital Integration and Flight Simulation from Psion.

Even though we haven't really got into the age of space travel, it's already possible to puchase so-called simulations for home micros. By far the most outstanding package is Elite from Acornsoft on the BBC. The 3D effects in this game have to be seen to be believed. Codename Mat on the Spectrum has some very clever 3D effects, proved extremely popular when it was first released and still has a good following. Interdictor Pilot from Supersoft is available on the C64, and Activision has released a space shuttle simulator.