The beginning of this game is the epitome of unnecessary tedium. If an enemy reaches the end, you actually lose gold, so you need to reach a certain point for it to become idle. How much is that? Well, you'd probably need 3 basic towers, which each cost 30 gold. A starting enemy drops 0.5 gold, and takes 3 clicks to kill.
In other words, it takes roughly 540 clicks on moving targets before the game can handle itself. That is a superbly unreasonable investment, as even idle games with slow starts fully kick off before 150 clicks maximum, on a stationary target.