The game is great but don't collect the 2600 version there are other versions that match the arcade more closely.
Of course if you are reading this I think you have played it somewher eby now It is in every Mario Advance game series it's the battle mode in super mario 3.
Other than that what is mario bros on atari 2600? A Blocky version of the arcade and NES versions, jump on turtles battle with the other green plumber go through large green pipes.
It's great if you did not own a expensive console of more power or the upcoming revolutionary NES back in the 80's but not so great now