CatmullRom

way to steal the photo from ddoi...

check it here:

http://www.flickr.com/photos/wvs/2599183575/in/set-72157605747668823/

Or, if you do the research you will see it actually IS playable in a manner of speaking.

http://www.2020.ro/dislocation/janek.htm

And the original Kotaku story from a few weeks ago:

http://www.kotaku.com/gaming/space-invaders/the-playable-space-invaders-carpet-184836.php