Myst

Enter code 724 in the safe inside the cabin

On classic mode, the code for the safe inside the cabin is 7, 2, 4.

On random mode, flip up the switch on the pedestal in front of the wooden cabin. Go back to the Myst library and look at the map. Adjust the knob on the map so that the white line coming out from it aligns with the outline of the cabin on the map (the line on the map will turn red.) Ride the library elevator located behind the bookshelf up to the observation deck and check the plaque on the wall beneath the key symbol. The combination is written here. Use this three-digit combo on the cabin safe.

Author's commentary: The lighter inside the safe appears to be a piezoelectric starter, while the original 1993 version of Myst had you using a box of matches to light the furnace. I can tell you from experience that this made relighting one's water heater's pilot light much easier than the old match method.