Ohhh, thank you! :D
Ye, simple timers for every wave haha xD and yeah, the balancing is almost non-existent... The book was meant for a cheap starter and after you've built some money with these you can upgrade. There is a description of all the towers on the itch page :p the drums deal HUGE AoE damage, they are busted xD But true, ingame popups or something would have been nice.