Did not expect my post to immediately follow the last, but I have managed to create a functioning sprite editor that is fully compatible with the Gamehut Tutorials.
You can create a sprite of any size and have that data converted directly into assembly code for the Megadrive. It allows creation of custom palettes and previewing of sprites using different palettes in the editor. Palette data is also converted to assembly which can be inserted into the code. Fully tested to work with the GameHut tutorials and imported into gens.
Still a work in progress, requiring both saving and loading of palettes and sprites to be implemented, but it works as a quick method to draw up a sprite and quickly import it into the code.
Created using JavaFX the application will require Java to run.
Download link can be found on my Dropbox here.
https://www.dropbox.com/s/gcqjumusyorpyfr/MegaSpriter_v1.zip?dl=0
I hope people find this useful :) It's been good fun to create it.
Good to know I have one fan! If you decide use it please tell me your thoughts on the application. I know I have to include saving and loading next (should not be too hard to implement), but I'm busy with other work right now. It's also uploaded on https://cmdrcrunk.itch.io/megaspriter where you can also leave comments if you like it. It's had 4 downloads so far, so it's making a major splash on the internet!