Crytek is working to release a Crysis 2 patch to correct two errors associated with multiplayer activation keys for the PC version of the game, a representative confirmed on the game's official MyCrysis Forums. In the meantime, the developer has laid out a workaround intended to side-step both users' inability to save their keys in the system (and thus forcing would-be players to re-enter the codes) and the erroneous error that claims, "Serial number in use." It's a three-step move, to be precise:
"Load Crysis 2, go to multiplayer and type in your key" "Navigate back to Single Player" "Go back into multiplayer and re-enter your key" The majority of responses in the forum thread indicates that the workaround does bypass the two issues, though apparently it doesn't ameliorate scattered reports of server crashes and game freezing; to say nothing of the two big topics on account login integration and promo code redemption issues.