I can't remember how I first learned of the original arcade game
Mario Bros., but my first exposure to it was by playing the Battle Game on Super Mario Bros. 3, and I can remember immediately making the connection when I first played the original. My friend "B" made the exact same connection when I showed him.
If Luigi was doomed to semi-obscurity thanks to being relegated to second fiddle in a largely singleplayer franchise, Mario Bros. is one of the few games where he matters. Inspired by William's Joust, Mario Bros. is build around a two-player cooperative mode, making the title apt. Super Mario Bros. is better remembered than its predecessor by orders of magnitude, but it was really Mario's game. This time it's about the brothers, and we wouldn't really see that again in a mainline title until 2009!
I played some co-op rounds with "B."
The influence from Joust is undeniable. This too is an arena-style platformer where your goal is to defeat all enemies. Joust forced you to make an aggressive follow-through when you unseated a foe by presenting the threat of having him remount on a more powerful steed if you didn't finish him off first. In Mario Bros., enemies must be flipped on their backs by hitting their platforms from below - go figure that this method predates jumping on their heads - and then kicked off of the level while vulnerable before they right themselves and become pissed off and faster. This can force you to ascend and descend platforms pretty frantically, but co-operation can make more efficient work of enemies, with one brother flipping a monster from below while the other is in position to finish it off right after.
The monsters aren't very fast and they move in simple patterns, though chaos can ensue when there's a lot going on at once. A big part of the challenge is the bros' slippery controls, which we felt like we spent just as much effort fighting as the enemies. This is best demonstrated in the bonus rounds, where the challenge is simply to collect ten coins distributed on every floor of the arena. Overall though, the difficulty ramps up slowly.
Notably, Mario Bros.' Japanese debut was just a day before the Famicom's launch, and its inevitable port came out only a few months later, though the U.S. release was years out still, coinciding with the system's nationwide release in 1986. As this port also qualifies for whale status, we played it too.
And it plays just fine. Graphical compromise was necessary, and to a greater extend than in Donkey Kong, but it honestly doesn't look or sound bad at all. The monsters' animations aren't as detailed as before, and the flipped turtles no longer jump out of their shells in their underwear when righting themselves, unfortunately, but it's a whole lot better than the austere treatment that Popeye got. It's also missing the between-level transitions, which is honestly fine. They only slowed down the arcade game once you knew what you were doing. And if I'm not mistaken, the "Game B" here actually ramps things up faster than the arcade game did, which as far as I'm concerned is a net positive.
GAB rating: Good, but play with a friend, because it's a bit boring solo. Joust is still the better game, both alone and in tandem, but Mario Bros. in co-oop is still good, slightly chaotic fun, where one moment you'll coordinate a perfectly timed maneuver and bump off several pests in a row, and the next you'll trip over your buddy's feet and plunge headlong into a fireball while he jumps right into a crab's pincers because you both went for the same coin.