The upgrade I miss most -- and I've heard may be covered by a mod -- is for explorers. They plod along at two hexes per turn. It takes dozens of turns to get them to the Progenitor sites or Sunken vehicles on the other side of the map. I would love to give them +1 movement, and eventually, hover ability. Nearly every game has one expedition site locked in the polar ice (either northern ice or southern ice) that no one can get to.
I usually send a submarine under the ice to collect the stray ice-locked resource pods, but they can't carry expedition modules.
I usually send a submarine under the ice to collect the stray ice-locked resource pods, but they can't carry expedition modules.