1. We know that space is, let's say, cold, and lava would just freeze.
Also we know that if lava will be drooped into water than ==>
In water, humans also can't breathe!
3. In space there is no gravity.
In water we can swim!
So you can fill space with a material similar to water, but with invisible textures. And game will became more interesting. Like, if hull will breach, you will die, if won't repear hull, or escape from that room.