It's a very good hack. @Von Fahrenheit actually pointed out many things, Here's my two cents:
- Neotame Fortress: the smashers can stay, but I've to agree. There's nothing that tells the player he/she's in danger. I suggest putting a sign or something that tells the player about them. Oh, and for some reason I can get hurt when I go behind the boss door. Weird.
- Neotame Nethers use a lot of these rising fire sprites. They're okay, but them seem to be used really frequently. I think they should be reduced a bit or mixed with other fire sprites, as it can get a little repetitive.
- Neotame Nethers 3: it's an unique level in this world. It doesn't use these fire pillars, but clever placements of Podoboos and Dry Bones. It's a cool level, but I encountered some small slowdown in the layer 2 section. It's minor though.
- Neotame Nethers 4:
Whoopsie. Minor thing, but it'd be good to fix it (missing corner above Mario).
One thing, but it's just my opinion - you don't need to redesign it, but it's just something I'd want to tell. Secret exits. Nearly every secret exit is easy or very obvious to obtain. This is something I kind of disliked. Your other hacks had less obvious secrets and they were better hidden. In this hack most of these were in the way and that made them really easy to get. It's not anything you must fix, it's just my personal opinion.
Anyway, I enjoyed playing this hack. Great job, Gamma V!