gog.com are running a promotion fight now where if you spend five, ten or fifteen dollars you can get up to three games at no extra cost.
This is in addition to the sale that gog themselves are running at the moment, with items like The Banner Saga series with 75% off. It however, should be noted that the games that you’ll get for free come from a selection chosen by gog themselves. Each tier of spendature will net you a game of your choice from Tropico Reloaded, Kyn and Breach & Clear: Deadline Rebirth.
Whatever your desire though it’s likely that you’ll find something you like over at gog, be it something old, something new, something borrowed or something blue. Happy hunting!