Alternate Reality - The City (1988) MS-DOS

One of the greatest games ever created. Way ahead of it's time in the way it implemented things like day and night cycles, diseases like scurvy if you don't eat vegetables for a long time, invisible karma points being tracked etc etc. 7 parts were planned, only 2 were released. This is the PC port of the first part 'The City'.

The Elder Scrolls - Daggerfall (1996)

The original open world procedurally generated RPG ! Very hard to play on modern PCs, even with DosBox, there is also a Unity remake out there.