Virtua Fighter 2 is free to claim till January 25th
Login to https://www.games2gether.com/ (Amplitude Studios official website) and click on the redeem button for Virtua Fighter 2. Valid until January 25th.
Steam store page: https://store.steampowered.com/app/71115/Virtua_Fighter_2/
You don't get a key, it just activates the game on your Steam account.
You can find this game in your Steam library as a DLC of "SEGA Mega Drive & Genesis Classics".