VECTOR

VECTOR is a Game Boy Advance game. Not a game about the Game Boy Advance, not a game in that style. A real 286 KB ROM that runs on the hardware, on a flashcart, on any emulator.

It is a homage to Valve's Portal, moved onto a machine from 2001 with a 240x160 screen, no floating point, no divide instruction and 96 KB of video memory. You shoot two portals, an orange one and a blue one, onto the pale panels of the plant, and you walk through them. You go in one and come out of the other, and the rule the whole game is built on is that you enter horizontally and leave vertically, or the other way round.

Twelve rooms, in two parts. The first six are a plant that still works. The other six are the same plant years later, with nobody left to shut the water off. Cubes to carry, throw and drop onto buttons; doors that need a weight to stay open; sentry turrets you knock over; laser beams you plug; moving platforms, elevators, bridges and lifts; falling water you can reroute through a portal and use as a weight. The last room is a tower two screens tall. At the end there is a closing screen. This is a demo, and it says so.

The camera moves. Every room is two screens wide, and one is also two screens tall. Walk into a room and the window sweeps to the far end and comes back before it hands you the controls: you get to see the room before you are asked to solve it.

It walks like it weighs something. The robot used to move at a sprint, with its foot touching the floor ten times a second. Now it walks. The leg is two bones with a knee that is found rather than drawn, the planted foot stays exactly where it is put while the body passes over it, every footfall has its own sound, and a landing arrives with a thud and a jolt of the window. The jump is exactly as long as it always was, because half the rooms are built on that measurement.

Everything is drawn by code. There is not one hand-drawn image in the project: the character, the walls, the portals, the water, the title and the fonts are all generated by a set of Node scripts that write out 4bpp tiles and palettes as C arrays, which are then compiled into the ROM. The room layouts are a text file, one letter per block, and there is a drag-and-drop editor that reads it, draws the real game pieces, shows the light cones, the laser runs, the machine travel and the jump arc, and on save rebuilds the .gba.

Written in C with devkitARM. No engine, no framework, no library beyond the standard startup code. Mode 0 tiled background, hardware sprites, hardware blending for the portal glow and the room-to-room flash.

Controls

D-PAD: walk
UP: jump
A: orange portal
B: blue portal
R: grab / drop a cube
D-PAD + R: throw a cube
L (hold): aim in 8 directions
D-PAD on a console: drive the machines

What it is not

A finished game. It is twelve rooms and an ending screen: a demo, a public work in progress. New builds will be posted here and written about at gerla.cc.

AI disclosure

The cover image and the title screen artwork were generated with AI, then reduced by hand-written code to the console's limits: 240x160 pixels and sixteen colours. Everything else in the game is drawn procedurally by scripts and not by a model: the character, the walls, the portals, the fonts, every tile and every sprite. The C source and those scripts were written with the help of an AI coding assistant, directed and reviewed by a human.