Ubisoft is celebrating the company's 30th anniversary by giving away a free PC game every month for the rest of the year, so starting off the giveaway promotion today, here is how to grab Prince of Persia - The Sands of Time
1. Go here
2. Click the small box to accept the terms
3. Click 'Get the game now'
4. Login / register a Uplay account
The game should then automatically be added to your Uplay account.
If you are not familiar with Uplay, it is Ubisoft's client similar to how Steam is Valve's client, EA has Origin, etc. so just keep that in mind as this is not a Steam game giveaway.