All the cool kids are playing it. Small(ish) browser game, addictive like 2048 (but nothing like it in style). You're a small ball that you can move with the mouse. You eat smaller balls that pop up all over the map (a big square). Other players (not sure the number...maybe 50ish) are doing the same thing. Here's the catch, they can eat you and you can eat them depending on who is bigger. The bigger you are, the slower you go. You can split in half with the space bar to flee or attack and the w key makes you splooge smaller amounts of your ball.
agar.io