This could be the greatest video game on the Gameboy Color.
When you first turn on the game, you get a load of options to choose. such as, the original 1985 Super Mario Bros, challenge mode, and the vs. mode. Other options include a list of high-scores, a folder with artwork that you can unlock, and the toy box.
The game play is just the original Mario Bros. Not much to say there.. There is a world map similar to the Super Mario Bros 3 one except you can't move in it, so I don't see a point for it being there. And if you beat the game with a score of 300,000 or more, you will unlock Super Mario Bros for Super Players. SMBfSP is actually the Japanese version of Super Mario Bros 2.
I recommend this for anyone in the market for a good hand-held game. The copy I bought was $10.