If you're a fan of strategic games than Humble has a bundle on for you. The Firaxis bundle contains a collection of games from the masters of strategy themselves, including some of their biggest titles to date.
First up is the $1 tier which everyone buying the bundle gets. That tier will net you turn based sci-fi game XCOM: Enemy Unknown, the classic high seas adventure Sid Meier's Pirates, the fighter pilot inspired Ace Patrol Bundle and the city builder Sid Meier's Civilisation III.
The second tier, for those paying more than the average price ($9.91 at the time of writing), will get you another two games in the Civilization series, that's numbers four and five respectively as well as Sid Meier's Starships and three expansion packs for your newly acquired XCOM game: the Elite Soldier and Slingshot packs. You will also get XCOM: Enemy Within for when you're done with all that lot and a 10% off voucher for Humble Monthly.
The top tier will cost you $15 and you get the latest entry in the Civilization series; Civilization: Beyond Earth. This comes with a side order of the Exoplanets map pack and a voucher for 33% off the 2015 expansion Civilization: Beyond Earth - Rising Tide for dessert.
Your purchase will support Humble, the devlopers behind the games and charity Action Against Hunger. If this doesn't convince you to go check out the full details then I don't know what will.