Gordon caught partway through Half-Life 2. Primarily intended for Milliways encounters, but can also be isekaied if he gets killed or a portalsnake gets him or Kleiner's portal goes (differently) haywire or the Nova Prospekt portal goes haywire.

Since I don't yet feel competent to write Alyx Vance in completely novel scenarios, for now there's a restriction that this Gordon can't find Milliways while Alyx is fetchable, and can't be isekaied in a way that includes her or makes it possible to bring her over after the fact.

"The right man in the wrong place can make all the difference in the world. So, wake up, Mister Freeman. Wake up… and smell the ashes."