I'd recommending adding some pitch randomisation on your talking audio to make it less repetitive and nicer to listen to. I'd also suggest making the tooltip show up instantly rather than animating before displaying as you have to display lots of tooltips to see the numbers, actually if the numbers were displayed next to the pipe that would make it easier to add up if you want people to have to do the maths, if you don't then displaying the current total number in the top left as you place pipes would mean you don't need to do the maths to add up the totals for all your pipe pieces. Cool spatial puzzle game where you have to consider the time cost as well. I like that all noises were made by you as well.