Portal: perpetual gifting initiative

perpetual [per-pech-oo-uhl], adj. continuing or enduring forever; everlasting.

Once again, it's the worst Steam sales ever, like every other Steam sales ever! And that means we celebrate the times when Valve was doing things with original IPs. For the 18th time in a row, it's my privilege to give away two games that deserve a spot in any library:

• Portal
• Portal 2

Veterans of this initiative will know that people who've already got Portal(s) won't go home empty-handed. Have an alternate puzzler on me, something mystical and strange.