graph TD
Player
Rocket
Cannon
Cannon-Ball
City
Timer
Score
Player -- spawns --> Rocket -- destroys --> Cannon-Ball
Cannon -- spawns --> Cannon-Ball -- destroys --> City
Timer -- increases --> Score
style Player stroke-width:4px, fill:lightblue
style Rocket fill:lightblue
style Cannon stroke-width:4px, fill:red
style Cannon-Ball fill:red
style City stroke-width:4px, fill:lightblue