This global parameter starts at 0%. This percentage compares to Earth's 21% oxygen.

The oxygen level is measured as a percentage of an atm of pressure, meaning that this percentage is comparable to Earth’s 21% oxygen. At 14% the atmosphere resembles that of Earth at a 3000 m elevation. This symbol means that you raise the oxygen level 1 step, and therefore also increase your TR 1 step.

Related Rule(s)