What issues are your encountering with the game? Does it stop working when launched? Does it display an error code?
1. Did you install the redistrutible files (Direct X setup, and VC redist) which came with the game?
2. Do you have the proper and latest drivers installed for your graphic card?
Once I encountered an issue with Splinter Cell Conviction (Steam version) (Splinter Cell series is another game serie from UbiSoft - same developer of the Assassin's Creed series), the issue was with the UPlay which came with the game download. It was an outdated version, I downloaded the latest version of UPlay, and it worked fine.
Which version of the game do you have, from Steam, physical disc or a pirated copy?