Rolling miasma

You start to explore this section of the space station, there's no strong reason to search any particular part of it just the overwhelming importance of staying safe. Something had clearly gone terribly wrong.

Where was everyone?

The emergency lights flicker as you stalk down the corridor. That was odd behaviour, in test runs and practice they stayed on and were off at all other times. The rest of the lights on this level seemed to be failing too, dimmed and slowly growing darker. Moving around in the dark was now a possibly and it wasn't a welcome one.

The door to your left was closed. The key pad entirely lit up, illuminating all the numbers and special characters, rather than just the numbers. Like the lights on this level the door circuits might also be acting up. That would be awkward as the most direct route to the arms locker was through that door and there should be a first aid kit on just the other side.

Before you can give the door and dodgy key pad a second thought you catch sight of motion from the corner of your eye.

Rolling down the corridor, coming from the direction of the barracks, came a silent and thick miasma.

The mist was grey, thick as pea soup down by the floor, thinning slightly towards the ceiling. It wasn't moving quickly but it was moving, slowly edging in your direction.

The movement of shadows, or perhaps it was just your intuition, suggested there might be something in the swirling fog too. Every now and then a bulge of miasma would form on the wavefront, a darkness behind it, before dissolving away.