The level you got there has potential, but I think you need to change a few things:
- The music doesn't fit with the level. I suggest something more lava/magma-ish, like
Melty Molten Galaxy,
Super Meat Boy-Hell or
Butsutekkai.
- The second section is just kind of there. Some of the background mountains are just floating mid air (or are they supposed to stand on the black blocks in the background?). The two hammer suits make the part really easy, because you can snipe the goomba's easily, and all that's left is just a simple maze. You could either remove the hammer suits and/or add some roto discs. You could also consider redoing the entire section.
- The first jumping koopa kind of ambushes you right at the start, you could replace it with a normal koopa.
- The venus fire trap between the spikes doesn't spawn.
- I believe smbx might crash when a mushroom falls in the lava. Although this didn't happen during my playthrough, it might not be a bad idea to set the speed of the mushroom to 0 with npc-codes.
- Your level uses the wrong exit. You need to use the SMB 3 Star exit.
- I personally don't like it when a level uses three different kind of goomba's. This is just nitpicking, though.
As I mentioned, the level has potential. The first section has nice aesthitics and some solid design. If you change the second section and the music, the level will improve greatly.