Gmod started out with just a rope tool... something like that in cortex command by itself would be awesomeness. The grapple gun is close to it, but it only connects to you.
And, of course, the rest, like the weld tool, thruster tool, and the wheel tool (who knows how that would work in 2d), along with the ability to fixate things.
A physgun with a working tractor beam that you don't have to bring really really close to your target to use and turn very carefully to move it like the existing one would be great as well.


Any or all of these would be great.

There's nothing exactly like what you described here, but you can check out TLB's FBM CB 4200.