Really great game - my favorite so far! I like how making the game easier is tightly bound with making the game a bit harder (at least temporarily). Though, I did kinda cheese it by not picking up the dropped clocks, waiting until the end of a wave, and then buying stuff for both the 30-second refill you get + the dropped clocks. :D
Just one minor thing I noticed - it seems you can't really "sell back"/put down a part you picked up but haven't placed down yet. I would appreciate it if I could change my mind. But I really enjoyed it nonetheless, thank you for making it!