Most of all I remember "Creature of Havoc" ( https://en.wikipedia.org/wiki/Creature_of_Havoc ) as being amazing and extremely hard. Instead of being an adventurer you play a monster with limited IQ forced to unravel the mystery of your own existence. It employed various techniques that prevented cheating like "If you have the key, add the number written on the key to this page number to open the door". One of those puzzles still has people discussing it http://laurencetennant.com/bonds/creatureofhavoc.html ( contains spoilers ). At 13 years old it took me and a friend 2-3 months to finally crack it.
Most of all I remember "Creature of Havoc" ( https://en.wikipedia.org/wiki/Creature_of_Havoc ) as being amazing and extremely hard. Instead of being an adventurer you play a monster with limited IQ forced to unravel the mystery of your own existence. It employed various techniques that prevented cheating like "If you have the key, add the number written on the key to this page number to open the door". One of those puzzles still has people discussing it http://laurencetennant.com/bonds/creatureofhavoc.html ( contains spoilers ). At 13 years old it took me and a friend 2-3 months to finally crack it.