Mass Effect 2 is now free for a limited time on PC! To take advantage of the offer you'll need to setup an EA Origin account and download the game via that service. According to Eurogamer, the events of Mass Effect 2 will flow right into the events of the upcoming Mass Effect: Andromeda, so that's likely the reason this is happening.
If you've never played the game, check out a trailer below. If you've played the game and know what a great deal you're getting...download it right here.