Assassin's Creed. I've just completed my first assassination in Damascus, and I'm having loads of fun.
Sticking a knife in the back of my target, and then running away was quite awesome. I went into this tunnel thingy, climbed up to the wooden beams, and then jumped from beam to beam until I reached the end of the tunnel, grabbed onto a metal bar, and stylishly leaped into a haystack below me, where I remained hidden for a while until all the soldiers dispersed.
The escape sequences are kind of like that awesome Tangiers chase scene in Bourne Ultimatum.