You can watch the five-minute video here to hear the game's creative director James Green explain AirMech while he plays it. Or, you could open up a browser in Chrome, go to the Chrome App Store, look for AirMech (it's here), add the game's app to your browser and start playing the beta right now.
Your choice. Either way, enjoy!
AirMech is in public alpha on Chrome. It's also in a private alpha on PC. Green hopes to bring the game to consoles and maybe Vita as a downloadable game some time in the future, too.