Calling this Colossus was. I presume, a carefully calculated strategy to reduce us wordplaying reviewers to the punful state of calling it 'colossal'. Well, as far as options and games go, it obviously is fairly... err... mega-good (Phew!) but when it comes to the instructions and general presentation it loses the odd point.
Colossus 4 comes from a long line of highly rated chess proggies, much favoured by addicts. I wouldn't claim to be a Grand Master - in fact Psion's 1K ZX81 program usually beat me hollow - but even to the sort of player who loses his queen after only five moves, the strengths of Colossus are obvious.
If you want proof that a CPU is better qualified for quick thinking than the old grey matter, you can even watch it sorting through all the possible lines of play as it prepares to thrash you. The manual boasts that Colossus crushes Superchess 3.5 and Cyrus IS, which is pretty impressive, by any standards.
For those into the game's more esoteric outposts, there's a good selection of time options, allowing for blitz games and the like, and you can set up the board for problem solving. Microdrivers have a bonus selection of classic games and problems to solve, while only the most daring players won't vanish at the merest suggestion of Invisible Chess, in which either or both sets of pieces are concealed, so that you have to memorise the positions.
If this sounds like driving round Spaghetti Junction with a blindfold, you'll be glad to know that you can control the difficulty by cutting back on how well the micro thinks - the equivalent in real terms of playing Karpov... with Motorhead providing a slight background distraction.
Unfortunately the 3D chess board graphics are small and rather indistinct. While moving the pieces is neatly controlled by a cursor, you could spend some time searching through the instructions if you want to know how to do something relatively simple, such as changing sides. Eventually I'm sure you'll get used to the multitude of control keys, but at first it can be an irritating diversion when you'd rather be playing.
Colossus is impressive in its options and should please anybody who's looking for some hard core pawn action, but if you want a prettier, albeit less demanding game, you may do better elsewhere.