Asteroids has to be one of the best, yet simplest games ever devised. If you don't know it, which I find pretty hard to believe, Asteroids had you as the pilot of a small triangular craft whose mission it was to destroy groups of large asteroids by shooting them repeatedly. As they were hit, they would split into two or three smaller pieces of rock. These smaller pieces would have to be hit and made even smaller until they ceased to exist.
Firstly, and the most obvious, is that the fast, smooth vector graphics have been replaced with slow, jerky sprites. All the asteroids now look like asteroids, rolling about the cosmos randomly. The backdrop has changed too. Instead of a bland black background, you now get nicely digitised views of space.
Probably the thing that has changed the most is the ship itself. Rather than one small triangle, you now have a transformable craft. It can change its size to suit its predicament. You have a choice of small, nippy craft that is very manoeuvrable, but has the lowest shield rating. Then there's the large lumbering monster that's almost invincible. The third is somewhere between the two.
So, what do you actually have to do? A large area of space has been taken over by Mukor, between 9 and 16 sectors depending on the difficulty level. You have to win back all the sectors by destroying all the asteroids in each. Between each sector is a map on which you can see which sectors you've cleared, as well as choosing which one to go to next. When you've cleared all the sectors, you get to fight Mukor himself, a large lumbering beast with more firepower than Tim coughing whilst eating a dry Cream Cracker.
In each sector, there are about five large monsters. One of these is coloured blue. As you break down the asteroids, one piece remains blue. When this piece is destroyed, it throws out an energy capsule. Collect this and it replenishes your energy back to maximum. Collision with an asteroid or practically anything else lowers your shield energy, at different rates depending on which ship mode you're in.
Alien spaceships also fly around the areas. Destroying these results in a goodie being dropped, either a two-way firing gun, or an extra shield. The one extra change? You can play one or two-player simultaneously. As usual, two player is much more fun.
Blasteroids is a very accurate conversion of an easily convertible coin-op with one major fault. It just doesn't have the fast paced action of the coin-op, and slow, sticky gameplay kills dead the quickness of reaction and speed of eye-to-hand co-ordination needed in a good arcade blast.
Rather than being a frantic, joystick wrenching blast, Blasteroids falls more into the category of a leisurely stroll, where the player makes occasionally almost subliminal move towards the computer.