Gonen32: Contact the site's owners and inform them of the TOS violation "or else.." , ban whoever they can find that trade keys.
RWarehall: Give them the information they are asking for, and it will get fixed. Others have done this before. Humble is just advising you, that you should be more careful and its not really their problem, but they do seem willing to help you this time. Else they wouldn't be asking you for the transaction ID. I read that as saying, "Don't make a regular habit of needing to contact us about this".
UnrealQuakie: I hope the best for you man, I myself got scammed for a shit load of codes from my humble bundle for a game here and the guy took off with I think 24 or something codes... I was an idiot beyond belief but I learned not to do anymore trades.
I hope they can solve this issue with that jackass who took off with the game...
I think I'll just drop it since I got the code from May's Humble monthly (which I unsubbed from later, and then subbed and unsubbed again for the June bunde). While not a TOS violation this isn't really the purpose of a monthly service and I don't want to draw attention, you know.
Anyway, I don't care much about getting the game (that I had no interest in to begin with) as much as I would like to game to be locked from the scammer's library.