PRISMA - ZX Spectrum

**The Monochrome King has stolen every colour from the Kingdom of Prisma and locked Princess Iris in the Grey Tower. Only Lume, the last ray of light, can bring the colours back.**

## The game

- 6 worlds: fields, desert, caves, ice, sunset and castle, each with its own look and music

- 24 platform levels plus 6 boss fights

- 6 enemy types: stomp blobs, kick shells into other enemies, knock the wings off bats, and time your way past frogs, spikes and flames

- Bosses take more hits as you go, from 4 for the Blob King to 10 for the Monochrome King

- Each defeated boss brings colour back to its grey arena

- Breakable bricks, and an extra life for every 100 prisms

- An original AY-3-8912 tune for each world, plus title and boss themes

- Classic difficulty: three lives and no continues

## Controls

| Keyboard | O left, P right, Q, Space or M to jump |

| Joystick | Sinclair or Kempston |

## How to play

You need a ZX Spectrum 128K, +2, +2A or +3 at 50 Hz. It does not run on the 48K or on 60 Hz machines.

Use the Tape Loader on real hardware or in an emulator set to 128K, then load `prisma.tap`. A `.sna` snapshot is also included.

The game has been tested in an emulated 128K. If you try it on real hardware, I'd love to hear how it goes.

## Under the hood

The Spectrum normally allows two colours per 8x8 cell, the famous colour clash. PRISMA halves that cell.

The 128K has two screen banks, and the display can switch between them instantly. An interrupt routine switches banks every 4 scanlines, 48 times a frame, in the short window when the ULA isn't reading memory. Each 8x8 cell becomes two 8x4 strips with their own colours. There's no flicker or interlacing, so it stays solid on modern LCD screens as well as on a CRT.

That routine takes up most of the frame, so everything else had to fit around it. The game uses flip-screen levels redrawn in about 3.4 frames, and sprites drawn with fixed-time XOR. All the art is built to the 8x4 limit, with dithered shading lit from the top left.

- Written in Z80 assembly, built with sjasmplus

- Levels, graphics, and music data generated by Python tools

- Tested with a custom cycle-level emulator and a bot that plays all 30 levels from tape to the ending

## How it was made

PRISMA was made with AI. Code, graphics and music were generated by Claude (Anthropic) under my direction, while I playtested and decided what changed. The story, levels and music are original.