Idk I haven't decided the name yet. I always believed that it works similarly to Super Mario Maker due to growing up with that game. Does it? I also want the plot and gameplay to be elaborate. How does SMB's level making process work?
I've had a bit of experience with rom hacks and have tried to hack SMB before. If you're wanting to make a rom hack you'll need a couple of things. https://www.romhacking.net/ <- This is a great place to look for tools.
1. A copy of Super Mario Bros rom file on your computer.
2. An NES emulator to run your rom. - I like to use OpenEmu
3. A SMB Level Editor - Find one from the link above
4. If you're wanting to edit sprites you can get a sprite editor too - Find one from the link above
Level designing is similar to Super Mario Maker but there are some limitations. Do you know why SMB ground is always flat? It's so that they could save storage. So when your editing levels you cannot place one individual ground tile. This is just one limitation among many others. You can find some YouTube videos that explain more.
Now, you mentioned wanting the plot and gameplay to be elaborate. This part will be a lot harder to do, as you'll have to edit the code itself. You'll need a hex editor for this.