There a lot of references…
In Metro 2033, a skeleton can be found, with a pair of glasses and a crowbar at its side.
In Splinter Cell: Chaos Theory, Anna Grimsdóttír remarks to protagonist Sam Fisher that “crowbars are for geeky video-game characters”, poking fun at the fact that Gordon Freeman is a scientist by profession.
In Call of Duty: United Offensive, two American soldiers are shown running side-by-side. On the left, Pvt. Gordon, and on the right, Pvt. Freeman.
In the Stark Towers level of the video game The Punisher, a scientist refers to another scientist as “Doctor Freeman” and asks what a noise he heard was, to which Doctor Freeman replies (paraphrased) “maybe the quantum physics department finally opened that extradimensional portal!”, with the other scientist replying “Extradimensional aliens! Wonder what they look like?”, a reference to the opening scene of Half-Life.
In The Ship, a game developed using Source, the description of the crowbar weapon states it is suitable for any “free man”.
In Destroy All Humans, the main character, Crypto 137, can read the thoughts of humans. If he scans the mind of a scientist, the player may hear “I must hurry, they need me in the test chamber! Oh wait, wrong game.”
In TimeSplitters: Future Perfect, during the level “Breaking and Entering”, Cortez, the protagonist of the story, changes into a lab coat along with a name tag that reads “Dr. Freeman”. He is also told, “remember, your name is Gordon, now lead on doctor.”
In S.T.A.L.K.E.R.: Shadow of Chernobyl, the player may find the body of a scientist named “Gordon Freeman” whose PDA makes mentions of Black Mesa, City 17, and a crowbar.
In the novel A Big Boy did it and Ran Away by Christopher Brookmyre, the author makes frequent references to various video games including Half-Life; one of the protagonists takes the alias of “Gordon Freeman” while there is an SAS soldier named “Shepard” (a reference to Half-Life: Opposing Force’s Adrian Shephard). At one point the male protagonist is equipped with a crowbar and the main action takes place in a largely underground hydroelectric power station with the Gaelic name “Dubh Ardrain” which can be translated as “Black Mesa”.
In the Left 4 Dead 2 downloadable campaign The Passing, Louis will sometimes say “Man, I feel like Gordon Freeman!” when equipped with a crowbar.
In console versions of Duke Nukem Forever there’s a control setup similar to the default control setup in the console versions of Half-Life 2 called Freeman.
In Fallout: New Vegas, one of the terminals is from Dr. Gordon, griping about the lack of cake at his retirement party. A reference to both Half-Life and Portal.
In Bioshock, the player is told to pick up a Crowbar or a Pipe Wrench, possible reference to Gordon Freeman’s Crowbar and Adrian Shephard from Half-Life: Opposing Force Pipe Wrench.
In the Doom mod Massmouth (as well as its sequel Massmouth 2), there is a chart with a list of names of people and planets they were sent to. One of the rows says “Freeman” and the planet “Xen”.
Also in the room right before this (the resting quarters), there is a room labeled “Freeman”.
Later in the story line for MM2 this room can be opened where inside you can fine a picture of Gordon Freeman as well as a (unusable) crowbar and HEV suit.
In Blue Shift and Opposing Force, Gordon’s model doesn’t have a death animation - if he dies, he will do the walking animation instead. However, his body can be destroyed.
In the Project Nevada mod for Fallout New Vegas, selecting a crowbar (a new weapon added by the mod) using the Pip-Boy will show a picture of the Vault-Boy wearing a hazard suit and Dr Freeman’s glasses.
In Walking Dead Video Game by Telltale games, there is a character named Mark who has a resemblance to Gordon
Guess I gotta go pick up a wired controller somewhere so I can get my Sonic fix…
