Learning MSX assembler for games development, where to start?

Wow, lots of questions. Let me see if I can help a bit:

To get started, I'd recommend just starting with something simple!
- Take your favorite text editor (I am not a big fan of VisualStudio Code that you mention, but if that's your favorite, then by all means, use that one), and copy paste this into a new file (e.g. "example.asm"):

; BIOS functions / MSX constants----------------
WRTVDP: equ #0047
LDIRVM: equ #005c
CHGMOD: equ #005f
SPRTBL2: equ #3800   ; sprite pattern address          
SPRATR2: equ #1b00   ; sprite attribute address         

; ROM header -----------------------------------
    org #4000
    db "AB" ;   ROM signature
    dw Start  ; start address
    db 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0

Start:
    ld a, 2  ; Change screen mode (Screen 2)
    call CHGMOD
    ld bc, 0e201h  ; write e2h in VDP register 01h (activate sprites, generate interrupts, set 16x16 sprites)
    call WRTVDP

    ; Define sprite:
    ld de, SPRTBL2
    ld hl, shipsprite
    ld bc, 32
    call LDIRVM

    ; transfer sprite attributes to RAM:
    ld ix, spriteattributesRAM
    ld (ix), 64  ; y
    ld (ix+1), 64  ; x
    ld (ix+2), 0  ; sprite pattern
    ld (ix+3), 15  ; color

loop:
    halt  ; make the program run at 50/60 frames per second

    ld hl, spriteattributesRAM + 1
    inc (hl)  ; increase x

    ;; Update the sprite attributes in VRAM:
    ld hl, spriteattributesRAM
    ld de, SPRATR2
    ld bc, 4
    call LDIRVM

    jp loop

shipsprite:
    db 00h, 00h, 01h, 01h, 01h, 03h, 03h, 07h, 07h, 0fh, 1fh, 3fh, 3ch, 18h, 00h, 00h
    db 00h, 00h, 80h, 80h, 80h,0c0h,0c0h,0e0h,0e0h,0f0h,0f8h,0fch, 3ch, 18h, 00h, 00h

    ds 8000h - $  ; fill the rest of the ROM (up to 16KB with 0s)

    org 0c000h  ; RAM
spriteattributesRAM:
    ds virtual 4

- This is a complete example to create a ROM that moves a sprite, and should show you how to get started in creating a ROM, set up the video mode, how to create the main loop, etc.
- It's time to compile it! Choose an assembler. I like Glass http://www.grauw.nl/projects/glass/ because it's simple, cross platform and open source. But feel free to use another one. Other typical choices are tniasm (proprietary, I don't recommend it), pasmo, sjasm, sjasmplus, asmsx, etc. (or you can even use my own "MDL", but it's a more complex one to use, so, probably not for beginngers). Assuming you chose Glass, you can compile with:

java -jar Glass.jar example.asm example.rom

- And there you go! you should have a rom file compiled!
- You can now just run it in openMSX, or your favorite emulator
- For debugging, I recommend openMSXDebugger
- For drawing graphics: as you can see in the example, the sprite is defined directly in code. But there are many tools. Honestly, I recommend using a general-purpose tool like GIMP, and then just write your own scripts that convert the graphics you draw into whichever format you want it for your assembler code.
- For music, I guess that's a bit more involved. So, maybe next time around, but basically you have two choices: (1) you can do it your own (send commands to the PSG yourself, write your own playback code), or (2) use an existing tool like TriloTracker that have assembler libraries for reproducing music. If you are going to work on small MSX1 games, I recommend (1), since existing trackers/players are pretty large and would use a significant chunk of your cartridge. If you are thinking of a larger game (megaROM, MSX2, etc.), then definitively (2).

Anyway, I hope this helps and can get you started. You can take the example above, and start editing it, building from it (maybe you can try to take that example, and make the ship controllable with keyboard/joystick as a first next step :) )

Thank you Santiago! The sample code gives me a place where to start, it is really useful. I can understand the code, except the very last line: ds virtual 4 What's "virtual" and why the "4" value?

@DamnedAngel: I want to go the full ASM way. Programming-wise, what is the difference between ROM, BIN and MSX-DOS executable?

That's a wise choice. Easier and more clear. You really only need any text editor (the simpler you can get is perfectly good for the job. But one with fancy colors and stuff sometimes saves you some work) and an Assembler. And some doc, sure
All you need to know is your machine, Z80, VDP and PSG (mostly, for a start). And, for a start, the BIOS is your friend.

That's an option too. The templates do support that and have the hello world ready for you, with a build script to automate the compilation/assembly processes in a neat manner and generate the symbol file for openMSX debugger.

Of course, other assemblers/tools can help you as well and you may find similar features.

ROM is a image suited for cartridges, but nowadays can be easily run fom MSX-DOS using tools like SofaRUN/SofaROM or ExecROM.
MSX-DOS is a program to be run form the S.O. natively. Your program is located on RAM and has *almost* the full 64kb space to deal with, and probably more with a memory mapper.
BIN are programs you run from MSX-BASIC with the command BLOAD.

From the programming perspective they are very similar.

Normally games are made in ROM format, which opens the possibility of a physical cartridge version. I personally like the MSX-DOS format, with games that can be called from the S.O. *AND* eventually return to it without booting the machine. But unfortunatelly these are quite rare.

Yep, cross compilers can output binary format too.
Developing cartridge games (roms) allow to avoid loading times. And problems like drives' malfunctions (they happen often, in 30-40 years old machines...