Paradox Shift, a first-person game in development by a bunch of students at the University of Southern California, is a puzzler. Sort of like Portal. Only instead of moving through space, you're moving through time.
Playing as a construction worker on a dam, you're given a time travel gun because, well, it's a lot faster to build stuff if time never actually goes anywhere.
As you can see in the video above, it works kind of like recent shooter Singularity, only with more emphasis on puzzles.