Well, it officially existed.
What you're looking at is a screenshot of the original file used for the final Half-Life 2 box art, created with Softimage XSI.
The specific Gordon Freeman model from Half-Life 2 was never officially released by Valve, with the promo art version reportedly painted over by Dhabih Eng. A lower-quality version of the model later appeared in the Japanese arcade game Half-Life 2: Survivor.
Unfortunately, if a Valve-made version of the HL2 Gordon model does exist, it's unlikely we'll ever get access to it, aside from a few renders we have (like the one shared by TheJeremy).
Valve
However, there are fan-made efforts to recreate it as accurately as possible, like this one by Gordon Freakman, who used the leaked box art XSI file screenshot along with other promo materials to rebuild the model:
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