This game is a harder expansion of the original with some slight mechanical tweaks and palette-swapped tougher enemies, on those fronts it succeeds and can get much more challenging than the original or its arcade-exclusive revision, you are absolutely expected to have beaten and mastered the original and its controls to get into this one early on, but the later levels do get a bit overboard with some annoying beginners traps that you would only know existed from prior knowledge, as such doing the 1up trick is highly advisable as otherwise, you will probably begin to run dry as it escalates in challenge.

Graphically the game is almost identical but the tweaks and additions they made are generally all improvements, the font is more legible and easier to read, the mushrooms and many other background objects now have faces for the first time and the ground tiles look more naturalistic.

This being an FDS game you'd expect some usage of its additional hardware capabilities but sadly outside the theme when you rescue the Princess it's all exactly the same as the first, a missed opportunity to be sure.

Quite a lot of the hatred this game gets is understandable as on the face of it is a brutally hard and otherwise almost identical sequel, considered by some to be a prelude to the extremely hard kaizo hacks Mario games nowadays or similar ultra-hard indie platformers like Celeste or Super Meat Boy, but Lost Levels is the first of its kind and is generally viewed much more fondly in its home country than the rest of the world, perhaps because the Japanese audience took to heart that this is a game for those that had mastered the original and not something to be played sequentially straight after finishing the first. The game itself even emphasises that fact with two secret worlds after finishing the game once, World 9 which is an obvious reference to the minus world from the original Famicom version of SMB1, and upon beating the base game of Lost Levels 8 times you unlock worlds A through D. Given that World 9 can only be beaten in a single life, they obviously didn't expect anyone but masters to be able to complete such a challenge despite its relatively short length. The other additional worlds are merely an extra for those who are willing to go the distance, not something everyone needs to experience to feel satisfied completing the game.

On the whole, this is a competent, if derivative, sequel to SMB1 but I can see why NOA passed on it back in the day both for its similarity to the original and high difficulty, but with appropriate context and expectations this is a solid challenge for the SMB1 veteran.