The first screen of Osmos is a text display of Newton’s third law: For every action, there is an equal and opposite reaction. You’re forgiven if you expected a Darwin quote. After all, Osmos is a game in the tradition of flOw and Spore, where you play a mote who eats other motes to grow big and powerful. The difference in Osmos is that you have to eject mass to propel yourself around the environment (hence the nod to Newton). So as you strive to grow bigger, you’re obligated to make yourself smaller. That small innovation is the difference between a game that makes a superficial observation about “survival of the fittest” and one that hooks into a deeper sense of simple motion.

This is a physics game in disguise. The apparent goal of gobbling up everything in sight proves to be a mirage: Your real object is economy of motion. Better to drift through the ether picking up smaller opponents than to expend half your mass trying to grab the mother lode. Once you learn that harnessing your momentum is the way to grow your own mote, Osmos responds by gradually shifting the color of other motes from red to an incandescent blue, indicating that you’re big enough to consume them. These lava-lamp visual effects do far more to set the mood than the cloyingly mellow synth tunes in the background, whose hip, weary tone is quickly becoming an indie-game cliché.

Osmos’ stages are split into three independent tracks. On one track, the only challenge is to grow as big as you can. Another introduces artificially intelligent creatures into the mix. Osmos thrives on the third track, where the stages incorporate gravity and orbital motion. The visual aesthetic of these levels is much the same, but the metaphor is different. Suddenly, you aren’t a bacterium in the primordial soup, but rather a little planetoid, fighting for your existence in the firmament as you careen around a pulsating star. When you give yourself a tiny push to shift into the orbit of a smaller mote, there’s a sensation that the galaxy is falling into sync with you. It’s moving in every sense of the word.