Space shooter game for SNES

This is my first project for the SNES, written in assembly using ca65.
It's written from scratch - I didn't use libraries that add a lot of functionality. This includes the tools I used to convert graphics, which I wrote myself in python (you can find them in the /tool/ directory)

• DPAD - move around
• B - shoot
• A - move faster
• Win if you get 420,000 points! (send me screenshots if you do lol)

You can get the ROM here
Not tested on real hardware, but works on Mesen and bsnes.
Snes9x does NOT work - and seemingly any other emulator that cares about the ROM header.

How I made this

I always wanted to make a game for the SNES/NES, inspired by YouTube videos about Mario 3 TASs and other explanations of very low-level computing concepts on those consoles.
Now I decided to look up a guide on SNES game creation to make my own game. The most challenging part was beginning - I've never wrote assembly before this, and many concepts (like SNES's 16- and 8-bit modes) were very foreign to me. Later on, though, I kinda got into this and realised assembly isn't actually as hard as I thought.
Thanks to Alex Ren for the background graphics - I have 0 experience in pixel art, so at least something in the game looks good :)

Building

• Get ca65 and ld65 binaries on your PATH.
• Run ./build.sh in bash.
• You will find game.sfc, main.o and main.list in the repo root directory.

Graphics tools

The game uses BG mode 1 (4bpp) layers 1 (titles) & 2 (background).
I wrote my own python scripts to convert .png files to SNES bitplanes, tilemaps and palettes. Those are in the /tools/ directory and require the imageio library (except charmap.py).

• bitplane.py is used to convert .png files into bitplanes with the pallette appended at the end (used for /gfx/charset.asm, /gfx/palette.asm). Doesn't do anything to fit in the 16-colour limit, so you have to keep track of your palette yourself.
• tilemap.py converts a .png file to a tilemap (used for /gfx/tilemap.asm). Every colour in the .png represents a different tile, and you will need to set the attribute bytes for each one yourself at the end of the output file.
• charmap.py generates a character map (used for /gfx/charmap.inc) for the compiler that's different from ASCII (since my font isn't full ascii and I need to use different offsets).

Resources I used

• Wesley Aptekar-Cassels' guide:
  https://blog.wesleyac.com/posts/snes-dev-1-getting-started
• Retro Game Mechanics Explained's SNES Hardware Features series (that's where the images from /reference/ come from)
  https://www.youtube.com/playlist?list=PLHQ0utQyFw5KCcj1ljIhExH_lvGwfn6GV
• Hardware register docs
  https://wiki.superfamicom.org/registers
• 65c816 opcode list (very technical and useful)
  http://www.6502.org/tutorials/65c816opcodes.html
• The docs to ca65, the assembler I used
  https://www.cc65.org/doc/ca65.html