Have a GOG.com account? You should, if for no other reason than to hit up promotions like this. For 24 hours, the digital distributor is offering first-person puzzler Magrunner: Dark Pulse for free. It's a decent enough game that you might as well add it to your library.
This deal is part of the site's summer sale special, which is also running some tempting bundles today -- the Bullfrog lineup for $9.79, the original Thief trilogy for $5.97, and the Wing Commander series for $9.52, to name a few. GOG.com is doing the hourly flash sale thing, too, so check back in. (Or don't! The Steam sale will be here before we know it -- pace yourself.)