reported region locking to your region (EU, NA, BR, ASIA, etc)
Australia: "Killer is Dead and DI:Riptide if bought in Australia cannot be redeemed in EU" - punisher51

Enter as own risk. I am not sure if region locked. Humble did not say it was, but people are reporting it. If you cannot redeem I would ask that you grant a reroll as I will not be getting a different copy. IF it is region locked, it is locked to NA. I was going to lock it down to NA only but there is no option for that.