TOWARDS the end of 1986 that rarest of rarities, an original game, was released by Firebird. Called Sentinel, it was the latest masterpiece by Geoff Crammond, who earlier had proved that the BBC Micro could support top class software with such efforts as Aviator and later the excellent Revs, still regarded by many as the definitive driving game.
Sentinel consists of 10,000 landscapes, each containing a Sentinel and up to six Guardians whose life energy you must absorb before gaining access to another landscape.
Each landscape is rather like a contoured open plan chess board with valleys, mountains and plateaux on which trees abound. The key to the whole game is energy. The smallest unit of energy is a tree; boulders are worth trees and Sentinels three.
Sentinels are like giant Oscars that slowly rotate on their elevated platforms. Whenever a Sentinel, or Guardian, turns to face you, it begins absorbing your energy, randomly redistributing it throughout the landscape in the form of trees.
The only way you can absorb the energy of the Sentinel, of its Guardians, is by reaching an elevated position in the landscape from which you can look down on its platform.
You can only absorb an object's energy when you can see the square on which it stands. You start each level in the lowest point of the landscape, often only able to see the tops of a few trees and the Sentinel towering above you.
Getting high enough to be able to absorb the Sentinel is in principle simple, but far from easy in practice. Imagine you're standing on the ground with an empty square beside you. You can create a boulder on the empty square. Then, on top of the boulder you can create a "copy" of yourself into which you can transport.
You're now standing on the boulder looking down on the 'old' you which you can absorb so as not to have lost any net energy, except that tied up in the boulder.
From your new vantage point you can see bits of the landscape visible because of your extra elevation. You may already be able to see the bases of a few of the trees the tops of which you saw earlier. If so, absorb their energy, you're bound to need it later to create more boulders.
And you're not limited to just building one builder at a time either. Apart from the fact that each one costs two units of energy to create, there is nothing stopping you building a tower of boulders before placing yourself on top. But although it allows you too make big jumps in height, having so much energy tied up in boulders proves to be too risky a strategy.
As soon as a Sentinel or Guardian starts sapping your energy you have to transport to a safe part of the landscape or risk premature death. This means leaving behind all the boulders. Although from your, hopefully, safe point on the landscape you can begin reabsorbing the boulders, you are now competing with the Sentinel which, even though you've moved, will still absorb any other energy source it sees.
Frequently, a policy of little and often is the key to success. Move from place to place, always staying one step ahead of the Sentinel, without ever having too much capital invested in boulders.
Compared with earlier 8 bit versions and the ST conversion released late last year, Amiga Sentinel, programmed by Steve "Goldrunner" Bak, is faster and has been given a complete sonic overhaul in the form of an incredibly atmospheric set of eerie, almost surrealistic, sound effects and musical cameos courtesy of David Whittaker.
Although the lack of effort put into Amiga conversions is often disappointing, Firebird has wisely decided to stick closely to Crammond's original 8 bit graphics, although they are brighter and crisper than in previous versions.
Any attempt at major modification would have been a big mistake, purely because the original was so perfectly crafted.
If you've never experienced Sentinel, treat yourself to the nearest thing yet to the perfect game. Unless you're an out and out death merchant you won't be disappointed.