Very cool game! I've found all the mushrooms. I didn't understand the meaning of the picture on the cave, and what are the holidaymakers, tough. Any tips?
The picture is a reference to an old computer game called 'Hunt the Wumpus' - a game credited with being one of the very first survival horror games. The Wumpus is illustrated in textmode.
https://en.wikipedia.org/wiki/Hunt_the_Wumpus
The holidaymakers memory is findable a few layers deep near a hillside.
Congratulations on finding all the mushrooms!