The "game" I have chosen for it is called "My Super Mario Bros 3". Having no relationship to the actual Super Mario Bros 3.
Made by author DUICU ALEXANDRU who seems to be one of the better level designers for this thing.
This is probably one of the hardest sets of levels I tried out, although it is still labeled as "intermediate". There are some fairly hard jumping puzzles that were a decent challenge for a SMB veteran like me and I hope they don't get you too frustrated.
Here's a link to the level on the NES Builder page:
To download them is weird, you have to rename them to .mario extension, otherwise they don't work with the game. Or you can download it directly here:
Screenshots of the first 4 levels:
This is just level 1-1, I love it :)
Watch out for this gap
This is the aforementioned jumping puzzle. I find it fun :)
Things are starting to get devious once you get to the first Bowser's castle..
Well, there you have it. Round 6 will run as long as we like, until we get tired of this. When we finish or get tired of this set, we can either choose a different Mario NES Builder set, or we can end the round and pick a totally different game :)