If you haven't played Portal yet, now is your chance. Valve is offering the Mac and PC versions of the 2007 physics-based puzzle game that took the world by storm for free on Steam until September 20.

Valve is giving the game away in honor of its Learn with Portals program. The educational program hopes to leverage the way video games are increasingly playing a role in education by using Portal and Portal 2 to teach physics and critical thinking skills to students. According to Valve:

One of the biggest challenges in teaching science, technology, engineering, and math is capturing the students' imaginations long enough for them to see all of the possibilities that lie ahead.

Using interactive tools like the Portal series to draw them in makes physics, math, logic, spatial reasoning, probability, and problem-solving interesting, cool, and fun which gets us one step closer to our goal-engaged, thoughtful kids!

Education or not, the game is addictive and fun as can be. Be sure to grab it before the 20th while it's still free!

Hat tip to Lex Friedman.

This article was originally published on Tuaw.
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