https://steamdb.info/app/1543590/
It's more of a tool I think, but it's classified as game on Steam. Anyway, if you add it this way it is free.
Couple methods to do it:
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Click the green install button on the SteamDB page
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AddFreeLicense(643141) for browser
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javascript:AddFreeLicense(643141) for mobile
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ArchiSteamFarm: !addlicense asf s/643141
Steam store page for reference (not free): https://store.steampowered.com/app/1543590/Wildshape__Map_Editor__VTT/