The Humble Store, opened as a year-round Humble Bundle aside from the actual Humble Bundle, is turning a full year old very soon, and to celebrate they're doing what they do best: offering awesome deals to gamers and sending the proceed to charity.

The Humble Birthday Sale includes some incredible deals, including Metro Redux for 50% off and 10% off a pre-order of the upcoming PC port of Valkyria Chronicles, but the best part of this sale is the deal on Metro 2033: 100% off.

That's right, if you put your email address into the designated box on the Humble Store website between now and 10AM PST tomorrow (that's 1PM for the EST crowd), you'll receive a full copy of Metro 2033 absolutely free. Metro 2033 is an excellent choice for this, as it's a criminally-underplayed game that those who played and like Metro: Last Light might want to catch up on.

As always, 10% of all sales made in the Humble Store go to charities like Child's Play, the American Red Cross, and the Electronic Frontier Foundation, so if there's a game you see as part of the sale, pick it up there and let some of your hard-earned money help those charities help people in need. It's rare that one can give back to the world in a manner as easy as this, so let's take advantage while we can.