A ventilator can serve three floors (one up and one down), but you should have a trained dweller work it to generate sufficient oxygen - so build the gym first, before you go down deep. The amount of oxygen available for free is less for each floor you go down, so the first four to five floors can be used safely without ventilation.
Ventilators provide oxygen only for the floor they are on, and the surrounding floors. You can watch them in action in the "x" resource bars, there is one bar per floor.
I try to cover a wide spread from simple to complex, from easy to hard, from fighting to puzzle, but usually I have to have at least one technical challenge in it for me to program.
The disk version may not run on all C64, it has a fast loader integrated and may fail with a patched ROM on either C64 or 1541 - you can try the single load .prg s
The game requires true drive emulation on the TheC64. Just rename the file to "mineshaftgap_AD.d64" and the emulator will use this mode. The downside is, that the game load times are much longer. You can solve this problem by saving a game state on the intro page, and for all future runs just load this game state.
It works fine on my C128 and on Vice in true drive and iec mode, but I can reproduce the issue on my TheC64. I will let you know, once I find the problem.
I just verified again, that it is working by using a vice screen recording. Without overtime the fuel tank lasts for 15 seconds and with overtime for 30 seconds. So it seems to work.
If you can't build a mine, you have run out of metal. The building menu shows the resources required for each building. If the building is shown in red, you have a lack of resources, if it is blue you have not researched it yet.
The top floor has infinite oxygen, so the oxygen meter starts with the second floor. Thank you for the bug report, I will look into the menu reset issues later to day.
Having no native hardware split screen options on a C64 one is kind of limited on the art side, when trying to do smooth scrolling with an independent left and right display.
A cartridge version with cut scenes, more graphics, multi SID support, story, more units, multiplayer etc. would be an option, it this genre should resonate with a big enough C64 crowd
