I've just completed replay this amazing games last week. Last time I remembered play it probably somewhere middle 90s using my Intel 286 machine.
You probably need to download the manual(from my collection) to unlock the last puzzle. Previously I pick the game from this link (with manual), but requires players suchs as ScummVM(figure out yourself) but if you kind enough you can buy it directly from Steam Games here which simplified with direct installation.
Truly a good game with simple command to play. Suitable for kid as well, developing simple logic thinking to exploit clues to solve a puzzle. Truly evergreen game. Can be use on Winxp & Win7.
Try it!