I looked last month at a couple of adventures from Topologika that have a medium difficulty rating. This month it's Acheton, with a rating of "a real challenge". This was first seen on the BBC Micro and is a first rate derivative of the original Colossal Cave adventure.

Acheton is only available on disc (CPC and PCW) and is text only. The aim is to solve devious puzzles and collect as much treasure as possible; the plot, as such, not having any real bearing on how you play.

The style is dated, with scrolling text and a limited parser that will not accept multiple commands, no ram save/load and, like other games from Topologika, no EXAMINE.

The parser appears to reject an input if it does not understand every word typed in (many modern parsers look for what they can understand). A few attempted commands will mean that the location description has scrolled off the top of the screen. You then have to LOOK (no short form L) to see where you are and what you have in the way of listed exits.

Mapping is important, and certainly in one or two places you will not get back to where you started by going NE, S, W. Acheton is a big game and will keep you occupied for a considerable time.

As with the Topologika games mentioned last month, there is an excellent system of helpful hints on tap. In a printed list you look up the item, place or character that is giving you trouble. Via a further question, this will give you a number to type in to the computer and up comes a hint. If this is not enough, you may be offered others.

The bulk of the action takes place undergound - and to get there you will have to climb a tree! Everything you find will either be useful, a treasure or both. Try not to waste time playing games, and study the habitats of strange creatures.

It is surprising how quickly we have all become used to the improved parsers and facilities of even run of the mill adventures produced today. Acheton is a little dated, but give it an hour or so for you to become accustomed to its lack of modern conveniences and it will keep you happily busy for days.