Battlefield 4 is the next game to feature on Origin's Game Time deal as you can play the game for free for an entire week.
Once you have downloaded the game you will have 168 hours to play the game for free, and the timer won't start until you hit the big shiny play button.
You just need to make sure you have Origin installed and then all you need to do is head on over to the game time page.
They are running this promotion as part of "Battlefest 2" which allows players to gain double XP, bonus Battlepacks and more. You can find out more about it and the schedule of the things to come, here.