Demon's Souls
The multi player is a little interesting as it allows 3 players to cooperatively play together, but 2 of the 3 players play as Souls rather than full powered characters. You can also "invade" other player's games as Souls and attack them while they play.
Game play Video:
<div style="width:500px; text-align:center"><embed type="application/x-shockwave-flash" width="500" height="319" src="http://gamevideos.1up.com/swf/gamevideos12.swf?embedded=1&fullscreen=1&autoplay=0&src=http://gamevideos.1up.com/do/videoListXML%3Fid%3D23921%26adPlay%3Dtrue" align="middle"></embed><a href="http://gamevideos.1up.com/video/id/23921" target="_blank">Demon's Souls 'Lost Soul' gameplay HD</a></div>
there are more video's but my internet is going to slow at the moment....
http://gamevideos.1up.com/video/id/23922