Here in England, Street Fighter X Tekken will be released on March 2nd. I will be getting it on the 3rd. I'm so excited, that I'm going to (actually already started) make an Atari 2600 version of SFxTK. This will be te first Atari game I've ever created so could you give me some tips? My goal is to create a game where you pick from: Ryu, Ken, Kazuya or Nina and fight against a CPU (or maybe a player). My idea is that if you press "Right" and "Fire" your character will punch facing right and if you press "Left" and "Fire" your character will punch facing left.
It sounds like a cool project and an ambitious one too for your first 2600 game. I've been working on a fighting game design for the 2600 too so I'll give the 411 with some suggestions.
-You'll want to forget about scrolling and just use a very wide panoramic background graphic. The majority of your graphics resources will be going into the 2 fighters. Also forget about background sprites unless you can draw them into the Playfield(EG.Onlookers/Ambient), better to spend your cycles on the player sprites and produce the best possible gameplay experience.
-Stick to 2-line kernels for the fighters at least and consider thicker line rendering for everything else as you'll want fast smooth animation and fast gameplay responses.
-Try to make the fighter sprites as small as possible sounds like an obvious statement but its very true. Try Street Fighter 2 on Gameboy and then try Street Fighter Alpha on Gameboy Color, much smaller sprites but way more fun to play and a better compromise for an 8-bit platform . The widescreen letterboxed background should help make the fighters appear proportionally taller than they are.
-Standard 8 bit wide player objects won't cut it so you're going to have to use Missile and Ball extensions for any wide stances of the arms and legs.
-You mention a directional based approach to fighter moves "Right or Left+Fire=Punch", I suggest using a Mortal Kombat setup to achieve the full fighter move set as it is an intuitive logical approach.
*Down Back+FIre=Roundhouse Sweep
*Down Forward= Crouching Punch
You'll also want tap and hold detection on the Fire button so you can tap for basic moves or hold Fire then perform a joystick move and release Fire to execute special moves.
Well that's all I got, I wish you much success in your project.