Here is a sheet with some enemies I would suggest to be added: https://www.spriters-resource.com/custom_edited/mariocustoms/asset/136823/

-Goombud
-Spike Top (red and blue)
-Banzai Bill
-Muncher
-Monty Mole (two kinds, hopping and chasing)
-Boo
-Spike
-Aimed Fireball/Iceball Piranha Plant (like SMB3)
-Sledge Bro
-Boom Boom and Para-Boom Boom

Also I'd like to suggest some para-enemies which doesn't require new sprites, such as the Para-Goomba and the Para-Spiny from Super Mario Maker.

I also made a SMB1 Gao sprite for SMBX, maybe you can use that?

Enemies I am interested to sprite if you want:
-Bony Beetle
-Thwimp
-Para-Beetle (SMB3)
-Mega Mole
-Sideways Thwomp
-Other Super Mario Land enemies

A different way to control the game, so now you can play it with one hand.

How to jump: Press up
How to duck: Press down
How to shoot a fireball: Press down, and you will shoot a fireball before you duck.
How to run: Press the left or right twice within quick succession, like in Kirby games, and you will start running. Running will be turned off once you stop moving.

A suggestion for alternate ways to display the game:

-Pixelated: The original SNES-version sprites. They are scaled up 2x to fit the size of Mario Forever.

-HD: The SNES-version sprites now redrawn to be the size for Mario Forever, without smearing like in the original.

I am willing to help with sprites for either of these ideas if they are accepted.