The very good 4X strategy game Age of Wonders 3 went free for a brief period a couple of months ago in the Humble Store Spring Sale. Did you get it? I have good news if your answer is no: It's free again, this time directly from Steam.
And why is it free now, you wonder? To mark the upcoming release of the next Age of Wonders game, Planetfall, which—as rumored in February—will be out on August 6. Owning Age of Wonders 3 will also get you a ten percent off the Planetfall pre-purchase price, so even if you're only really interested in the new game, you might as well snag the old one (if you don't already have it) to get the deal.
Age of Wonders 3 is free on Steam until July 15. Age of Wonders: Planetfall is available for pre-purchase for $50/£42/€50.