It wouldn't really matter how good or bad this program is - as it is the only Electron version of the original Colossal Cave adventure, I'd have to recommend it. So it comes as a bonus to find that this adaptation is superb.
I haven't played the original Crowther and Woods version so I can't say how close to the original this is. However, it seems to have all the problems I have read about so it must be a full - or nearly full - adaptation of the original.
In it you play the part of a typical greedy adventurer. You come hotfooting it, flushed with success from your last adventure. You've heard of the fabulous treasure to be found in the area and are eager to get your share.
Armed with the objects you find above-ground you race off to the grating that gives access to the labyrinth of caves below. You soon come across your first major obstacle - a large venomous snake. Its teeth soon puncture your ego as well as your skin. It is at this point that you realise that things aren't going to be quite as easy as you thought.
Careful exploration of the earlier locations soon reveals the solution - though the final answer is for the birds. You'll also find the first magic word. This returns you to the building but remember to turn off your lamp - it won't last forever.
You progress slowly, solving a maze and other puzzles and finally enter the main body of the adventure. Eventually you will solve the game but it is more likely to take weeks rather than days. Well, what else can I add? Very few adventures ever reach the standards set by this one. It is deservedly called Classic. Somehow it is exciting to visit all these locations I have heard so much about before. In a way it is like a legend coming to life. All I can say is it's a superb game and one that no true adventurer should be without. Magic!