Cool concept -- it's like a tower defense game but instead of towers you've got traffic lights.
Definitely took a minute to figure out what I was doing. One thing that would have really helped is giving the ability/traffic light icons on the bottom and right side of the screen some kind of feedback when they're selected, like an outline or something. I initially tried to drag the traffic lights onto the map, before realizing that I had to select one and then click to place. Same thing with the abilities -- I didn't realize that I had to place them.