Truly a great simple, yet captivating, puzzle game. The background music is super charming and contagious. The color pallet a joy to look at. Truly loved the variety in hue, and the rich contrast. The gameplay, for the most part, just works. I must say I am very disappointed it doesn't have more levels, I NEED MOAR!
With all that last funny act aside, I think you guys have a great game in your hands to expand upon, and turn into maybe a full game. Doesn't have to be anything too big. I feel it needs more attention to detail in some minor but crucial areas.
One of the issues I had with the game was the line not spawning more times than I could count if you just didn't click at a certain angle. Other times it worked as intended. I also feel that, although very neat and helpful, the line snap would need to be made a little shorter in terms of detection.
Another issue I had, and i think this was the second most annoying one, was having to go to the right side of the screen to change tools. Maybe some people won't care, but it breaks the immersion a tiny bit, and when you make more mistakes it dries out the fun out of the game. A few solutions could be:
Add a command that makes it pop next to the mouse cursor, but that you can switch and wrap around using the mouse wheel. You could also add a shortcut, let's say the S key, to switch back and forth the two modes. If you wanted to take this a bit further, allow the users to set a key of their liking to it, that way everyone's happy.
I think that's all. If this is the level of polish you guys can put out in a week I can't imagine a month. Truly wonderful work!