The hardest game I completed is Eye of the Beholder 2 !
Figuring out how to open the first door in the underground levels took a few months, then I realized that there was a button
Also getting multiclass characters with three classes was not a good idea for they could not level up easily and could not cast good spells soon enough. I restarted the game when I was about to finish it
so it took me about two years to complete the game but it was great fun. It's too bad that eob3 hadn't been released on amiga :/ (<--why don't we have a smiley for this?)
The easiest game that I completed is Defender of the Crown. In a few hours, the game was done