Audio and graphics are really nice and coherent.
The idea for the game is really good. When playing, it is hard to know when you can / are using the grappling hook, the feedback with the cursor is not enough for my taste.
A longer grappling distance would be better because it's really hard to hook things, i ended up mostly using the fly button and inertion to move. This would also make it easier to plan your path, tough this may also be made easier by increased the camera's FOV.
Great entry !