Traffic Officer — free browser game

You're a traffic officer at a four-way intersection: your goal is to let as many vehicles through as possible without crashing them or clogging the queues, and to raise your score. There are two signals at the intersection; either the north-south (NS) axis or the east-west (EW) axis turns green while the other waits on red. To switch the signal, press Space, click the intersection, or use the Switch signal button; each switch has a half-second yellow phase during which no one may proceed. Every vehicle has a patience bar that drops from green to red; if a driver's patience runs out the game ends, and you restart with R. As your score rises, vehicles spawn more often, patience times shorten, and red-striped ambulances appear — ambulances ignore the red but still stop on yellow, so try to turn the axis before they join a queue. Tip: don't switch the signal just because a single car has arrived; wait until at least two or three vehicles have built up on the other axis or a patience bar is close to turning red, and remember that the yellow transition is not a luxury.