X-COM: UFO Defense was an excellent tactical strategy game when it was released back in 1994. It was so popular that it spawned a remake in 2012 and a sequel last year from Firaxis Games. if you never played the original, now is your chance.

The Humble Store is offering the game for free until 1 p.m. ET / 10 a.m. PT tomorrow. You'll be saving $4.99, and get to play a classic in the process. You'll need a Humble account as well as a linked Steam account to get the game, and you'll need to redeem the key before February 15. 

And if you like the game, and you are a subscriber to the Humble monthly, you can also grab XCOM 2 for $12. 

Humble just concluded a redux of its Winter Sale with some good deals. And just because the game was created by Shacker jamiejme (aka Ndemic Games chief James Vaughan), I'll push Plaque Inc.: Evolved, which is on sale at the store now for $8.99, 40% off the usual $14.99.