Just want to be pointed in the right direction here...

Hello everyone, I'm currently making a Sonic 1 hack, but I'm a bit stumped. In my hack, I am making 2 (maybe more later) characters playable, I set it so at the title screen if you pressed a certain button, the other character's art would load, but I wanted to make them a seperate character as a whole (load different life icon art, goalpost art, different abilities, etc.)

Before anyone goes "We're not just gonna give you code, you fucking lazyass!" I just want to be pointed in the right direction, I don't need anyone to give me code, just maybe some tips or help to get me started. I appreciate any and all help, I'm kind of inexperienced with adding more playable characters to hacks.

 

You're going to need a flag in a unused RAM location, which you initialise when you choose a character (e.g. Sonic = 0, Tails = 1, ...), and then you use a cmpi.b plus beq.s or bne.s whenever the characters should do something different (e.g. look for art loading and put a cmpi.b there, and so on, you might even load different layouts and songs in this way). If you use beq, you will branch to a new label if the ID of the character is the one you want (e.g. cmpi.b #$1 and then beq.s will go to code dedicated to Tails); vice versa using bne.s will branch if the character is someone else (you can use it for a Knuckles' breakable wall for example).


Posting from a phone so excuse any inaccuracies but yeah this is as generic as I can be, good luck!

 

There are tutorials for adding different characters all over this site and Sonic Retro.  I suggest you start there.  They mainly tell you how to display different art by copying Sonic's art and replacing it; you do something similar for the move-sets, life icon art, etc.  Make a copy of it, change the copy, and have it load with your new character.  Also check out how Sonic 2 and Sonic 3&k handle separate characters. 

 

I would say start with Markey's 68k beginners tutorial to get a better idea of how this type of assembly works.

Then for adding new characters to Sonic 1, take a look at Sonic 2's files. If you've done enough research to understand how the engine works, it should be relatively simple.

I won't walk you through everything, but take a look at these locations in Sonic 2:


InitPlayers
This routine is what tells the game which characters to load.


Obj01

This is the Sonic player object, if you are going to make a custom character, chances are you want to use Sonic's object as the base, as it is the cleanest and most base of the characters you could modify.

Also, if simply reading Sonic's code isn't enough, you can try to read the guide to port knuckles to S2, this guide explains how to load up another character's art,mappings, animations and even their own life counter. Just adapt it to your own character.

I wish you luck in your future endeavors. 

 

How about something short and sweet?

Basically, you have to make the game ask which character to load

You can make Sonic 0 and <Insert name> 1. Sonic 2 does this. Whenever a level loads, it asks, is it Sonic or Tails that I need to load? You can do this by making Sonic move 0 into a free RAM address, and your other character 1 into the same address. When a level loads, have the game check what's in that address, and load the appropriate character.

On top of that you also need to have the character to load. You can do this by duplicating Sonic's object, and changing the labels (So instead of Sonic_Jump, Character_Jump, etc. so you know what's what and so the assembler doesn't freak out when you build.) You also need to give the character different art (obviously), and the things that go along with it, PLC, etc.

 

I'm planning on making a very simple and easy to understand tutorial on, this, acyually. Be on the lookout for that.