Playing the Atari version - using Atari BASIC - of AI's latest action-SF game is an absolutely amazing experience. Virtually all the typical criticisms of BASIC programs - which boil down to slow movement and poor control - are inapplicable. Neil Larimer's Rear Guard is a rousing success, a horizontally-scrolling multi-option blast-up that overcomes spare but evocative visuals to give players a blindingly fast arcade-style contest that compells you to keep playing.

Gamers man a huge, cannon-armed starship which can move in any direction. Pairs of smaller craft appear, moving across the screen from left to right. These two targets must be destroyed either by ramming (which drains 10% of all energy the ship possesses) or by a direct hit from the cannon. The targets enter at random times and in a variety of configurations. If possible, the player should maneuver the big dreadnaught between the two clay space-pigeons, moving up to take the prey that rises then dropping to takeout the low-flyer. Don't get down too far, Buck Rogers, hitting the terrain costs a full 10% energy drain.

The computer keeps lists of the number of hits, the number of escapees and the amount of energy remaining. Early on, if ten enemies get past the big ship, the mission fails and the craft crashes into the mothership. The enemy attacks in ever-faster waves.

Don't use up all your ship's energy by ramming but don't be shy about using the shields, either. It's better to lose some energy than to let four or five enemy ships slip past. After destroying about 50 ships, the first level of the mission is deemed a success and play resumes with a clean slate of escapees.

It's such a brilliantly simple game concept that it, of course, works perfectly. It's a reminder that fine software can still be created using BASIC and bolstered machine language subroutines. A surprisingly strong showing in the skill-action category from a company better known for its text adventures. Recommended.