Fun fact: before Ubisoft gave us their most successful franchise ever, it was going to be a Prince of Persia spin-off. Originally dubbed Prince of Persia: Assassins, the game later went on to become Assassin’s Creed. I’m glad it did! Somehow I can’t see a spin-off having been nearly as successful.
This has only recently come to light thanks to a demo reel put together by a sound designer who used to work for Ubisoft. The reel itself contains clips for a number of games, but the Assassin’s Creed bits start at about 1:30 or so.
As you can see by what’s in the clip, the game hasn’t actually changed that much. Sure, it’s clearly a very early prototype, but the basics are there. Even Altair’s outfit didn’t change that much. Also, it clearly shows that Assassin’s Creed guards were taking injuries to the knee way before anyone in Skyrim.