"Castle" was first created on a Challenger 2 in 1979 in 8K!
It was inspired by the Adventure games of the time which I found frustrating to play and lacking in graphics.
Over the years, "Castle" has been improved and refined and moved from computer to computer. Today it demands careful planning, logical thinking and a dash of luck to play well. Yes, the Best Score of over 15 million is genuine - the game took about one hour and afterwards my daughter and I were both exhausted from the concentration required! I have tried to estimate how many different games are possible but it is near impossible - there are 15! (that's 15x14x13x12x11x10x9x8x7x6x5x4x3x2) permutations of the rooms alone!