Now that the RetroChallenge has started I'll explain what I'll do in October, involving the Sega VIC Dual hardware, a puzzle game targetting it and the Z80 assembly code.

About the specifications, the VIC Dual system is a color arcade hardware, has a 256x224 display and the orientation can be landscape or portrait, and some color games which run on it are Carnival, Tranquillizer Gun, Borderline, Pulsar, Head On, Head On 2, and others.

One highlight I like to make is Head On, which has a "eat-the-dots" gameplay one year before Pac-Man. I'll use the Head On 2, a landscape color game to run my assembled output by replacing the ROM binaries.

Head On 2 game running on MAME

For the game that I'll develop later on, it's a puzzle game called SameGame, it was created by Kuniaki "Morisuke" Moribe under the name CHAIN SHOT in 1985, it's played on a rectangular field with blocks placed at random, and the goal is to remove as many blocks as possible by selecting a group of two or more. I'll base it on the Flash game version by Jussi Kari, which contains power-ups:

Samegame Flash version running on Ruffle

The Sega VIC Dual system uses the Zilog Z80 CPU, so I'll use the same zasm assembler which I used last year. I think the Z80 assembly is a great assembly to work on, with extra opcodes available compared to the 8080 assembly.

For running it I'll use the same strategy as last year, which is assembling the code, split it into eight files of 1024 bytes, and replace the Head On 2 ROMs with the custom ROMS, that means I have 8K ROM size to work on.

To start working on the hardware I executed two test ROMs on MAME from the 8bitworkshop website, one example tests the color display and another tests the VRAM tiles (the outputs are rotated because the test ROMs were designed for portrait output):

Testing the color display (Source)

Testing the VRAM tiles (Source)

So for the conclustion this project is kinda a follow up from the previous year which I worked too on an arcade hardware, the difference is that instead of a black & white display I'll work on a color display, and instead of 8080 assembly I'll work on Z80 assembly which means there's extra opcodes available.

PS: I couldn't upload the images directly with the image button when creating a project log, so a workaround was to upload the images as files and getting the link location.