If you want to go straight to the game, just read the brief instructions at the page linked below, and you'll be ready to play. The game will load quickly. If it doesn't respond right away, hit the New Game button to get its attention.
The game gives a fairly accurate simulation of the reaction time needed to at least make contact with tennis serves of various speeds. The ball crosses the on-screen court in approximately the same amount of time as would occur in a real tennis match. For the serves of Greg Rusedski (149 m.p.h.) and Venus Williams (127 m.p.h.), that amount of time is remarkably small.
127 miles per hour is 186 feet per second. A tennis court, baseline to baseline, is 78 feet long. If a ball were to travel across a court at a constant speed of 186 f.p.s., it would take 78/186 of a second, or approximately 0.42 seconds.
Fortunately, for anyone trying to return Venus's serve, the speed of the ball is not constant. Air resistance, plus the friction with the court upon the bounce, slow the ball (on a hard court) to roughly half its original speed by the time it reaches the opposite baseline. The ball's forward speed slows more on clay, less on grass.
Given that the ball starts at 100% of its full speed and ends at roughly 50%, its average speed across the court is roughly 75% of its full speed. So, for Venus's serve that starts at 127 m.p.h., the ball's average speed is 127 x 0.75, or approximately 95 m.p.h.. This equates to 139 f.p.s., so crossing the 78 feet of the court would take 78/139, or 0.56 seconds.
The Rusedski serve, at 149 m.p.h., would move at 219 f.p.s. in a frictionless world, taking only 0.36 seconds to cross the court. In reality, though, it takes all of 0.48 seconds. No sweat, right?
Of course, tennis doesn't enter the computer realm without limitations. For one thing, I would not recommend trying to return Greg Rusedski's real serve with your mouse. I'm quite sure that its tennis career on a real court would last for exactly one click (more like a crunch, really).
The Java Tennis Serve Return Game makes a number of compensations for existing in ones and zeroes. To make the ball visible, for example, it's the equivalent of the size of a beach ball. Even at this size, though, it would be too hard to hit with an exact mouse click, so clicking within a diameter to either side of it counts as hitting it. This reflects that fact that your swing in returning serve has some timing latitude: you need not swing at precisely the right millisecond to produce a decent return.
Enjoy the game:
