I got Far Cry 3 on Steam. Wanting to play it, I downloaded it, and after a couple of hours, I started it up. Instead of starting the game, it started UPlay. "Alright", I thought, "I'll just start it through UPlay." Activated the key on UPlay, pointed it to the correct installation path (in the steamapps folder), and hit... 'download'? Wait what?
UPlay wouldn't recognize it as being downloaded, causing me to having to download it again. Luckily it only took 3 hours, but I was still kinda pissed.