Shoot at your own face in this neat tech demo.
Face Ace was one of the few playable 3DS demos, and it began by taking your picture. Following that, your head was transformed into a floating 3D head that reminded me of the Game Master from Retro Game Challenge.
You were then instructed to fire at the incoming 3D faces, all of you. You had to move the 3DS around to fire at the enemies, which stuck out their tongues in defiance.
The entire experience was like System Flaw, a DSi-exclusive title that featured a similar use of the outside camera on the DSi. However, the 3D effects made the experience more compelling and playable. It was a lot easier to figure out where each enemy was with the 3D effects.
Face Ace wasn't listed as a tech demo like other demos there, but there's also no confirmation that this game will see life outside of E3 2010.