Atmospheric Density Display
So how exactly are newer players supposed to know that they can use atmospheric thrusters on the alien planet? There’s no way of knowing if there’s even an atmosphere! Sure you have the O2 gauge showing if the air is breathable or not, and you got the temperature which only matters if you run out of suit power.
My suggestion is to add a atmospheric pressure gauge to the HUD, next to the O2 gauge. This would show wether or not there is an atmosphere (breathable or not, that info is showed by the O2 meter) and how dense it is. Maybe have it measure pressure in bars, with one bar being equal to the pressure on the earth-like planet (as would in real life, 1 bar = 1 atm.) It could also tell you the pressure of a room, just in case the room isn’t fully pressurized. This value could also be displayed on the air vents UI along with the percentage.