Hey thanks for playing. I know people can exploit letting enemies reach the end and I'm totally fine with it, I wanted to make it easy enough for anyone to beat without punishing them and you can play it how you want. Adding the time buttons was a late addition but I'm really glad I did it. Not sure why the second and third towers didn't work for you, I tested the game a lot and never had that problem.
It's definitely worth beating once but you didn't miss much by not playing through again, just another theme.