The purpose of this simple guide is to teach a basic concept of colours, so the palettes in your Sonic hack don't look batshit insane.
One thing I've learned over time, specifically from a certain other forum that I will not mention, is...
JUST BECAUSE YOU THINK YOUR PALETTE IS GOOD DOESN'T MEAN EVERYONE ELSE WILL.
But it's all a matter of opinion, yes?
In most cases, no—opinions on palettes are, for the most part, universally shared.
I've seen a lot of hacks where the creator boasts about his palettes, and after playing the hack, they look downright stupid.
So don't be that asshole.
I might be that asshole, but most people from the past have seemed to love my palettes.
So, let's get started.
Load up that rom of yours into an editing program.
No disassemblies needed for palette editing :P
EDITS TO BE AVOIDED BY BEGINNERS
These are the palette templates that over the years, I've only seen decently executed by experienced hackers.
I. Changing the time of day. So, you want your GHZ to have a sunset feeling going on? Or you want your EHZ to be during the night? STOP RIGHT THERE. These will be your first mistakes. These two ideas should be avoided for two reasons:
A. They're very awkward to do if you're new at this. Sure, maybe the checkers will look a little lighter orange, but the grass might look like glowing radioactive stuff.
B. They're generic and over-done ideas. Seems like only the experienced hackers can make these two ideas look fresh nowadays.
II. The "Neon" look. Good. God. NO, GHZ will NOT look good with colours that match a rave scene. Don't even fucking try. I'll cut you.
III. The "Dark Re-Imagining" look. Dark colours, bloody grass, etc. I don't care what you say, LZ does not look "cooler" when the water is made red to look like blood. It'll make you look immature, I can promise you that.
It also makes playing on portable devices a pain in the ass.
EDITS TO BE AVOIDED AT ALL COSTS
These are colour edits that I've never once seen done well. They mostly aren't used by experienced hackers.
I. Making the grass some weird ass colour. It seems that only shades of green fit for grass because, well, it's grass, stupid. Making weird coloured grass makes your hack look too odd, people won't be familiar with weird colours, therefore, people will subconciously lose interest in it. It'll look like Sonic is on some alien planet.
II. Grey ANYWHERE. NO NO NO NO NO NO NO NO NO. Grey checkers in Green Hill? NO. Grey Marble? "OH but it's a castle stage" FUCK YOU MAKE IT BRICK. Grey Springyard? NO. Labyrinth? NO. Starlight? NO. The only exceptions to this are, in fact, the mechanical stages. There it will look cool.
III. Making night-time coloured stages day-time coloured. Kind of like above, but this will never look good, I've seen a lot of hacks where they tried to make Starlight look like it's in the morning, it looks like shit.
So that's about all for now. Before anyone starts bitching, keep in mind that I'm NOT telling you to follow this guide, but it will make things a lot better if you do. I've been studying art for a long while now, what colours do what to the brain, what colours pull you in or blow you out. Some hacks, if you haven't noticed, have done NOTHING but change the palettes, yet you keep playing because they use amazing colours that are not too "IN YOUR FACE" about it, they're calm or complimenting colours that pull you in and make you want to press on. One strategy I use for basic palette editing is starting with the darkest colour, then working my way up. Learning how darker colours contrast with the lighter ones can really help you when you're wondering what kind of feel you want going on in your level. But all in all, as I said above, it's all a matter of preference. What you choose to make of this guide is up to, well, you.