It appears that players have been taking full advantage of Assassin's Creed Unity going free for a week—so much so that the Unity servers were taken down for maintenance a few hours ago, in order to increase the server capacity.
Earlier this week, Ubisoft announced that, along with donating €500,000 to help with the restoration of Notre-Dame, it would give away Assassin's Creed: Unity for free, giving players a chance to experience the game's faithful representation of the historic cathedral.
The maintenance happened at 7AM UTC. If you haven't had a chance to grab it yet, you can download Unity free via Uplay or from the Ubisoft Store. Additionally, if you were unfortunate enough to have purchased the game immediately before the announcement, Ubisoft has said that it will refund purchases made through the Ubisoft Store after 2 PM EST on April 15.
Cheers, Twisted Voxel.