Mark of the Ninja
Dear everyone: this is the ninja game you have always wanted. You can silently climb walls, grapple between lampposts, shatter lights with throwing weapons, sneak through vents, slit enemies' throats from behind, and stash bodies in hiding places. You can opt to evade enemies instead of slaughtering them, if you're into that. There are unlockable challenge rooms. There are lasers.
Also, dear game developers: this is the ninja game you have always wanted to make. Sorry guys.
Progress: Breaching the Perimeter