Orbitous

Nothing is stationary. Every star system is fully simulated, constantly orbiting around the black hole in the center of the galaxy. Watch the worlds around you collapse, explode, and merge into new ones. 

Build better weapons to progress. Take an ordinary bullet and modify it into a shotgun, increase its mass until it's large enough to host orbiting projectiles, or add a field of heat to burn nearby enemies. There are many possibilities, and most modifiers are stackable.

Real time physics. After a bit of procedural generation, your fate is left to entropy. Watch lively worlds burn, your favorite shops be demolished, and the stars that once guided you burst into a thousand pieces.