From
OpenCulture.com:
"In the wake of the great Notre Dame fire, the French video game company Ubisoft has
decided to make its popular video game Assassin's Creed Unity free through April 25th, allowing gamers to "experience the majesty and beauty of the cathedral." The gothic cathedral figures centrally in the game. Start
your download (available only for PC users) here. Once you download the game, you’ll own it forever in your Uplay games library.