Heroica is focused on fantasy and an ancient past with monsters and magic. I suggest to make a space/future version of it. The basic game is the same, including the dice, expect that the shield side becomes replaced by a futuristic symbol of some kind. One exception to all battles, due to extended range of weapons you don't need to be next to a monster but one can attack even when two fields away.
Character classes are very similar to the fantasy classes
Marine - soldier that can take out all adjacent monsters
Medic - heals two point even to adjacent players
Scout - has a range attack
Smuggler - obtains one gold piece when killing a monster
Bounty Hunter - can charge at monsters two pieces away
Possible scenarios: Moon base alpha, alien space ship, lost cargo ship, alien planet, underwater base, science outpost, alien home world, mars surface, factory complex, future city