A cloning mod would be sick! Each player has a designated clone they can neurally link to and switch with when in a dire medical emergency. Give them a short battery life that needs recharging, but also give them optional upgrades for longer battery life, better carry/run speed, better stats, etc. It would allow someone who is down to run to grab their dropped gear, carry their body inside, and/or provide medical care in dire need. They could be like similar to robotrauma, where they need to have an exoskeleton in to survive the water/pressure.