thanks for playing!
the connector, which cost 1/1/0 to build, is needed to connect other towers. In the web version ,the collectors won't show light but the downloaded version will do. If a building is connected, they will show white light rather than red light.
you can take the connection system as minecraft redstone but have no length limit (though when the connection is too long it will slow down the computer, making the 3rd level almost impossible to pass. I will try to fix it when I have time)