Free: Guacamelee! Super Turbo Championship Edition (PC) $0.00 (Steam required)
Oldie but a goodie
Referrer receives ~$11 NZD in Wallet Credit for the first 30 brand new subscribers that signup for Humble Choice after clicking on a referral link.
great game i played this ages ago
Anyone claiming this remember that it must be activated on Steam before Friday, otherwise you'll lose it.