Dave Kircher Is a Supposed member of the Artifact team.
Dave joined Valve in 2005, fresh from the DigiPen Institute of Technology, where he helped create the mind-bending student project (and Portal precursor) Narbacular Drop.
His primary contributions to Portal and Portal 2 involved developing the graphics and physics systems that make the games’ unique discontinuous spaces work seamlessly in a 3D environment. With the addition of multiplayer in Portal 2, Dave then made those spatial discontinuities work with nonlinear prediction. Dave has also contributed to Left 4 Dead games and Xbox360 support for the Source engine.