Is this the first multiplayer game that Valve has designed from scratch?
-L4d was made by turtle rock
-TF2 was a sequel to TFC, made by the same guys
-DotA was already established by icefrog
-Counterstrike has only ever succeeded despite valve (and they bought it)
I guess it also depends how you look at it, but didn't Richard Garfield design (or help design) artifact? would this be the same kind of qualifier as l4d being made as turtle rock, etc?
and I completely agree with the post above me. sure, these games existed beforehand, but valve quality/polish/production turned them into masterpieces. Surprised Portal wasn't mentioned above too considering it started out as a student project and valve hired the students/project.