Just wondered if anyone else was playing this? It's a single-player game fairly similiar to portal on steam, so if you enjoyed portal you'll probably enjoy this. Instead of portals you use dimensions to make stuff lighter or slow down time. It was designed by Kim Swift who worked on Portal, and left Valve when they rejected her idea for adding dimensions and went to work on QC.
You missed the oppertunity to get the awesome tf2 medic labcoat if you haven't bought it already
but it's deffinetly worth buying for it's price if you liked Portal, enjoying it so far.