Ubisoft revealed at their E3 press conference back in June that they will be giving away 7 free games on PC as part of their 30th anniversary celebrations. One game per month will be made available to Ubisoft Club members (it's a free sign-up), and the first one was Prince of Persia: Sands of Time. Now the second game has been confirmed and it's a true classic - the original Splinter Cell. It's been more than a decade so don't expect it to be quite the same graphical powerhouse that you recall, but the gameplay is still intact.
The game is made available on July 13 (until then you can pick up Prince of Persia: Sands of Time) and will be a free download for 30 days.