The entire first season of the acclaimed new Hitman series/game is heavily discounted on Xbox Live - reduced from £45 to £18 - from now until 26th June.
Hitman's discount is part of an Xbox Live indie game sale - developer IO having rebought its independence from publisher Square Enix recently (retaining the Hitman IP in the process).
First-person puzzler The Turing Test is also heavily discounted, down to £4.80, in the sale. We Recommended The Turing Test in our review, calling it, "A playful examination of the relationship between human and machine, and a focused, entertaining puzzler."
The Major Nelson blog has a full list of games in the sale - I haven't heard of most of them. Note that the Farming Simulator 17 discount is reserved for Xbox Live Gold members only.