For those in desperate need, I have provided a few hints. Best to try
without them first, then if you are really stuck, read them in order until
you are no longer stuck.
There is also a complete walkthrough.
It can even be played in game via the 'replay' command. Note that this
is far from the only way to complete it, and should give you some ideas
for further solutions if you are interested in that type of thing.