When Atari came along with RealSports Tennis in 1983, it was fairly obvious that Activision's game was studied well. While RealSports Tennis was revolutionary like Activision's earlier title, the Atari game is more refined and is an absolute hoot to play. Frankly, I enjoy both of these titles and would argue both have their particular merits.
In terms of graphics, RealSports Tennis looks very good. Where the Activision players are restricted to one color and resembled stick men, the folks in Atari's version of tennis look more realistic and even appear to be wearing shorts. Instead of Activision's solid wall, Atari gave us a court divider which looks like an actual net. Finally, there's a convincing scoreboard in the background and players are even allowed to enter their names on it (up to eight characters, at least). And, yes, you even get a ball which casts a shadow (adding to the illusion of playing in a three-dimensional environment) and screen flicker was kept to a minimum. One very good feature is the fact the players run off the court when it's time to switch sides between games. Sure, that's a minor thing, but it adds to the sense of whimsy in the game. Whimsy is good. I like it. RealSports Tennis, while not overly-sophisticated, is a very clean-looking game which is downright attractive.
The computer opponent provides a good challenge, too. And, if the challenge proves to be too much, the right difficult switch is used to adjust the computer's skill level. There are two speeds available here - slow and fast. Unlike the Activision cartridge, the slow speed doesn't serve up a game (bad pun, bad pun) which simply crawls along. Indeed, the action is pretty brisk on slow speed and a bit more difficult on the faster setting. Want to make things more difficult? The right control switch (well, both switches in two-player games) determines whether the computer will hit the ball automatically or require the player to press the joystick button to smack it. Of course, two players can take part in this game, thereby increasing the fun of RealSports Tennis. There's nothing like two people gloating at each other as they score points.
If there's any flaw in this game it's the way the angles of shots are controlled. In Activision's Tennis, hitting the ball of the end of your racket is pretty easy, but the same is not true of RealSports Tennis. The rackets are considerably smaller, and it's easy to miss a shot completely. The problem isn't as bad as you might think, however. I can usually get the angle I want, but the fact I can zip by and miss the ball makes things more challenging. I will warn you, however, if you play it safe and try not to avoid hitting balls at steep angles, you'll wind up involved in some very long volleys.
And, speaking of zipping around, the control here is pretty darn good. The joystick is very responsive, and players can be run around the court quickly. That leads to the feature which allows players to select their shot power. If you're running toward the net when you hit the ball, you'll slam the rascal. Running away from the net will produce a lob, while moving from side to side or standing still will result in a "normal" shot. The shot power doesn't matter much most of the time, but I have been able to use the feature to my advantage on occasion. Including the ability to select shot power is a feature which adds a little more depth to the game. The fact the feature is so easy to use (hitting the ball is pretty easy, in fact) makes it even more appealing.
And, then there's the sound. Well, there's not much here, really. You get a convincing "thump" when a ball is hit or bounces on the court. Also, you get a beep when a point is scored, when a game has concluded, when a set is over and when the match is won. I'm not sure what more anyone would expect from an Atari tennis game.
Like I said, I enjoy the heck out of both Activision's Tennis and Atari's RealSports Tennis. The Atari game is just a bit more difficult to find, but I've never seen it on eBay or anywhere else for a ridiculously-high price.