Thousands of Steam codes - 7050 - for Sniper Elite 3 were apparently stolen from a PC game distributor and then illegally sold on to multiple outlets.
Neither Valve nor the game's maker - Rebellion (or publisher 505) - were compensated during any of this so "that set of keys" has now been revoked, developer Rebellion explained on the Steam forum.
Anyone who bought a revoked key has been offered the pre-order Target Hitler DLC as consolation. Rebellion listed the shops selling keys who weren't affected by the stolen stock.
"As a developer," Rebellion wrote, "Rebellion are happy for you to purchase the game anywhere you see fit and support price competition in the PC market. We have in no way targeted any specific vendors (who may have also thought these keys were legitimate), just this one set of keys.
"All we can suggest if you have been affected is to please contact your vendor and first ask for a replacement key, and then contact us for the free pre-order DLC if you are successful."
There was controversy among some shops when the issue first broke on Friday. PC key reseller CJS-CDKeys wrote a long post charting the issue, which seemed to suggest businesses like it were acting underhand.
Sniper Elite 3 topped the UK video games chart this morning - a chart that doesn't count Steam sales.