Luigi Bros. Classic is another hypothetical or fan-made game referencing the Mario and Luigi universe. Its 'Classic' moniker implies a style reminiscent of classic platformers, suggesting that the gameplay would likely involve side-scrolling levels, obstacle avoidance, and collecting items.  Without further details, its features and development remain unknown, and it does not seem to be an officially released NES game. It's a common fan-made variation or reimagining of existing Mario games featuring Luigi.

Luigi Bros. Classic

Low G Man - The Low Gravity Man (USA)