PPPPPPPPP is an Xbox Live Indie game that doesn't use controllers. All it asks is that you play with a friend, use your voices and sound like complete dorks.
The game's full name is PewPewPewPewPewPewPewPewPew (hence the abbreviation), and it's controlled using an Xbox 360's vocal input. Whether that be a regular Xbox 360 headset or, as in the clip here, Rock Band mics, the co-op title has one player controlling the hero's jetpack while another controls the gun.
It's "coming soon" to the Xbox Live Indie Games channel.