Playing this weirdly hypnotic game is as easy as moving your mouse pointer in the desired direction and clicking to speed up or slow down. As ethereal music chimes in the background, you aim at targets that look like tadpoles and other odd undersea creatures, wrap your mandibles around them, and voila -- you "evolve."
As you creature changes, it gets larger and more complex, a process you can speed up by targeting specific organisms -- you are what you eat. Swimming up translates as "zooming out," while swimming down zooms to deeper and ominously darker planes. In those depths, you'll eventually encounter hostile organisms composed of multiple glowing dots, which must be fully consumed to convert your enemies into benign and edible particulate.
How do you beat it? That's not really the point, but if you manage to swim to the ocean bottom and defeat the final enemy, you'll float to the surface and be reborn a jellyfish-creature, at which point you can run the entire gauntlet again.
Note: This link takes you to the vendor's site, where you can download the latest version of the software.--Matt Peckham