To celebrate the launch of Steam on Mac, Valve is being mighty generous with one its most critically acclaimed titles, Portal. And by generous, we mean that they’re just giving it away! Until May 24 you can grab yourself a free copy of Portal (normally $29.99) on either Mac or PC, although it doesn’t much matter considering that the game utilizes Steam Play, meaning that once you own a copy, you can access it on either PC or Mac without having to buy another version of it.

Considering that Portal has won over 70 Game of the Year awards and is widely considered one of the best games of all time, not only do we recommend that you go get it immediately, but we’d also like to take this opportunity publicly shame you if you don’t already own a copy.

Seriously. SHAME. On you.