It's really cool that you added gases simulation to the game. I'm thinking that the players will need some way of mitigating the danger of those gases which might otherwise make cave exploration near-impossible. I did some research, and curiously the most ancient way to ventilate mines was to light fires at the bottom so that the heat would create a ventilating draft. At the beginning they used brushwood fires. During the 19th century, the same principle was still in application in the form