The HD mod does NOT graphically improve the game as Logan might have implied with this line “if you want to enjoy HoMM III in impressive detail”, all it does is allow you to fit more on screen at once. I bought the full version off of GoG a year or two ago, and I was using the HD Mod until it stopped functioning and kept crashing a turn or two into the game (bloody russians) but this may have been fixed in more recent iterations.