The game itself is challenging. Nice for finishing the game using unreal in 48 hours!

This could have some potential

Very challenging, first person platforming is hard because you can't see where your feet are. The way the beams fall away is nice, fits the theme. For a stretch I would have asked for a double jump to give us a chance to course-correct.

Absolutely brutal. A little more air control would be nice! Level 2 was so much easier!

Very difficult. Like @laurenceogden said, either double jump or a bit more control in flight. Good job!

UE4s standard player character is terrible for this kind games. But anyway the idea is okay, and the music is good.

Concerned that this construction company won't be around to finish their project with all of these health and safety violations. Nice job on the game!

Such a serious approach to game! Liked your notes at github, and main menu background :)
Idea is pretty straight to the theme, but nevertheless interesting.
It's some hard to feel the character, maybe it's due the control, or maybe this is post-processing effect, or maybe physics, dunno.
And I'd add some diversity to the levels: maybe some opening-and-closing doors, raising beams, maybe some helping elements.
But you did well, good job!