Having it as a new game brings lots of possibilities! It can be all about managing newtonian physics, momentum, maneuvering different bases/colonies around resources and each other.
Right now I have a basic sketch of an idea, if you're interested in further discussion. This game is sorta based on some kind of space-plant/station blob thing. Lots of ways to reflavor it, and readjust the gameplay to complement the flavor.
1) There are two types of matter. Living and Nonliving. Living matter generally form large "Colonies" which slowly increase in size/population. Living matter suffer friction/slowdown/waste which means they don't travel forever. Nonliving matter are either floating resources which can be absorbed by living batter, or various projectiles ejected by colonies for various reasons.
2) For every reaction, there's an equal and opposite reaction. In order to move your colony, you need to sacrifice some of your mass as "reaction mass" which turns into energy/momentum, and sacrifice some of your mass as "ejection mass" which helps dictate the end speed of your two components.
3) Living Ejections can be used to form two, more mobile but more vulnerable colonies. Additionally, these colonies would be launched away form each other for a period (until slowdown slows them down to effective stillness) which would help them access resources without too much overlap.
4) Non Living Ejections travel onwards forever. This means that a large ejection mass can travel the game world for several days, before appearing suddenly out of "sight" and smash into another local region. It can smack into other large ejection masses and coalses into a large resource pile. Still uncertain if ejection masses should be resource rich nor not.
5) Combat. There's three types of combat. 1) Pure momentum combat is when you simply try to throw as much mass at something so that the two of you go in the opposite direction. 2) When living mass hits non living mass, some kind of "explosion". Right now, I kinda feel like each "hit" does a static amount of damage. This way, players can build up resources to make multiple ejections and so do more of the same static amount of damage, as long as they hit. 3) When living matter of different affiliations hit each other, some kind of combat occurs. The end result can be they bounce off, they stick to each other and continue combat, they merge and continue combat. It'll be interesting to develop!
6) For one basic idea, the damage caused by a nonliving to living "hit" is "static" (or at least, doesn't change based on mass), but the number of ejections (or cool down between ejections) allowed increases over time. Therefore, in the early game it might be worth going for larger momentum strikes to buy time, and in the late game it might be worth ejecting lots of fast, small nonliving particles to deal damage.
7) More complex, damage can be a function of momentum/energy transfer.
This idea is kinda a mess, but I can see how divorcing it from NP proper allows the mechanic to flesh out and come into its own!
EDIT: some of the ideas on making projectiles and aiming come from Aurora 4x.