I got snarfblam's save/load code to work for the following nestroid hacks.
You need to make sure they are expanded (385 kb).

- Captive
- Genocide
- Master
- ProjectRidien
- Revival
- RidleyX
- MetroidX
- ZebianIllusion

It only saves to the first file, but it's way better than a password system.
If you save on any other file, it will overwrite the first one.

The map wasn't showing the right tiles. I didn't even try the wave/ice combo.
It's a two hour hack job. I don't know nestroid. I just want to play the levels.