When judging a port of a successful arcade game, you look at how well everything about the game was reproduced: the graphics, the sound, the characters, the mechanics, and so on. Sometimes, however, all you have to do is ask a single question: If the port had been passed off as the original arcade game, would the game still have been successful?
For the Apple II version of Mario Bros., the answer is a surprising, but very definite, "Yes!" No, it doesn't look or sound exactly like the arcade game, but it does play exactly like the arcade game. Every enemy character, every personality trait, every strategy, every change in difficulty, it's all here. And while the graphics and audio aren't bit-for-bit recreations of the originals, they are as good as the Apple II can make them, and quite excellent in their own right. In short, despite running on one of the weakest platforms, this is hands-down the best 8-bit version of Mario Bros. released.
Except, truth be told, it actually wasn't released, at least not officially. When the video game industry crashed in 1983 and 1984, many of Atari's planned titles were shelved, even fully-developed titles like Apple II Mario Bros. Such games usually wouldn't see the light of day until years after the fact, thanks to collectors and former employees showing off their stashes of prototype cartridges and work disks. Mario Bros. however, was leaked to the Apple II pirate community soon after its creation, and quickly became one of the biggest hit games never published! Piracy may not be good for the industry overall, but sometimes it's the only way you can see a great game like this one.