Long before their adventures in the Mushroom Kingdom, Mario and his brother Luigi were just a couple of simple carpenters trying to make an honest living. However things didn't quite go as planned... From out the water pipes came deadly Turtles, dangerous Crabs, and worst of all Fireflies (from the sewer?)! Mario must team up with his brother Luigi and rid their house of these deadly pests forever.
Since it would be years before Mario and Luigi would begin experimenting with "Magic Mushrooms", they'll have to tackle these pests as plain old "non fireball slinging" carpenters. Your only weapon are your fists, which you use to smack the floor. When you hit the floor directly beneath your enemies, they will be flipped over and become easy prey for you to kick off the screen. However if things were really this easy you wouldn't need a buddy to help now would you?
There are three different types of enemies Mario and Luigi will encounter Shellcreepers, Sidesteppers, and Fighterflys. Each creature requires a special strategy to defeat as they each have different personality and method of attack.
If things start getting out of hand you can hit the POW bar at the bottom of the screen. Hitting the POW bar is like hitting every floor segment at once, and will hit all the enemies (assuming they're touching a floor segment). You only get a limited amount of POW, use it wisely! After a few levels fireballs will begin to randomly appear and cross the screen, so unless you want to be burnt to a crisp avoid them! There are two different kinds of fireballs in the game: Gold fireballs will stay on the level they appear, but orange fireballs will bounce around to different levels (which makes them especially dangerous). On later levels a nasty little monster called "SlipIce" appears and will freeze floor segments making you slip out of control. Try and knock off this little blighter as soon as possible.
Every time you successfully knock off an enemy a coin will come out of one of the pipes which you can grab for points. After a few levels you'll get to play a bonus round in which coins are scattered around the screen in various patterns. If you can collect all the coins before the timer reaches zero, you can score mega bonus points. However some bonus rounds have invisible levels which make them especially tricky.
Mario Bros. was programmed for the Atari 400/800 along side the 5200 version, but for some reason was not released. In 1987 during the XE years, Atari decided to dust off several old titles that had been shelved for various reasons. However while some titles like Crystal Castles were completed or updated using the original code, Mario Bros. was completely rewritten from scratch. It is unknown why Atari decided to scrap the original prototype, but they may have felt that it had not aged well. If you look at the title screen, you'll see that the programmer didn't bother to change the * and # symbols to Select and Option for the 8-bit release. At least one other game (Moon Patrol) also has this issue. The text on the 8-bit title screen is also highlighted for no apparent reason, this does not happen in the 5200 version and may be a side effect of the conversion process.
A prototype box can be seen in this picture (first row, tenth box)