Imagine that you're walking down the street one day and come across a giant screen where little triangular avatars are blasting one another à la Battle Tank. On the sidewalk are cheering men, posh women, grannies and kids, all clutching their cell phones and staring at the screen. If the MegaPhone project gathers any steam, such a diverse group of gladiators might be a reality.

Designed by Jury Hahn from New York University for Yahoo Design Week, the concept behind MegaPhone is simple. Any phone, from any plan, in any country can dial the number that appears at the top of a public game screen and — presto! — you've turned your cell phone into a game controller, ready to bring back the glory of '80s arcades. There's no software to download, and Megaphone also allows for voice control to perform such actions as reloading, ordering your avatar to devour pellets onscreen, or hailing a taxi.

A game on a MegaPhone could be a great way to kill time where a lot of people are queued up, like at theme parks or concerts. I'm not really a fan of gaming on cell phones, but if I came across a MegaPhone screen, even I would dial in. — Kevin Hall

MegaPhone, via Übergizmo