MPD stands for Martian Planetary Dollars, it's the unified currency on Mars like euros. It would probably be shortened to something like Mardol or Marsdollar in casual speech.
why is Val always alone on missions?
I have yet to explain the situation in game, but basically your unit is both an isolated special purpose squadron made up of only a few high power crawlers, and has been cut off from most supporting units that would typically join you in a combined operation. Later on I think you'll actually be fighting alongside friendly units and be joined by allied crawlers in combat, but for now you're just a psycho who's fighting all on your own.
10/10 great game.
looking forward to future updates!
Thank you! It's being worked on.