Titanfall will be going free-to-play this weekend, at least on PC, to kick of EA's Game Time program on Origin. What is "Game Time," exactly? Basically Origin users can try a game for free for 48 hours, at least when EA makes it available through Game Time. In this case, the featured game is Titanfall, and it'll be free on Origin starting now until Monday, June 23, 10 AM PDT.
Keep in mind that once you've downloaded the game, you've got 48 hours to cram in as much Titanfall in as possible. If you like the game enough to buy it, all your progress and unlocks from the Game Time trial will carry over. Now that's pretty considerate of them.
Anyway, remember that this is a limited time deal, so grab the download ASAP and get playing. The trial won't actually start until you've started the game, so don't freak out too much at the 21GB download (and 48GB install).