Cubix: How Gogin Achieved a Groundbreaking 3D Platformer on the ZX Spectrum

Retro gaming continues to surprise and inspire, and nowhere is this more evident than at this year's YRGB 2025—a prominent retro game development competition dedicated to the iconic ZX Spectrum computer.

Running from August 7th to August 20th, YRGB 2025 has ignited a surge in homebrew releases, including notable entries like Manu & Kit's Asymmetry and Miguelito's Escape from the Twilight Castle.

Yet, one title in particular—Cubix by homebrew developer Gogin—has captivated both players and developers for what it achieves: a true 3D platformer on hardware never designed for such feats. Cubix stands out for being described by its creator as "the first-ever 3D platformer" on the ZX Spectrum, offering players a Fez-inspired experience with dynamic rotating levels.

The game is structured as a puzzle platformer, in which players guide Bix, a small squared protagonist, through six expansive towers in search of talisman fragments broken by the villainous Hexatron.

Players navigate primarily in 2D, acquiring abilities that enable progression, while the entire level visually rotates once the edge of the map is reached, crafting a pseudo-3D effect unique among Spectrum titles. Reflecting on the genesis of Cubix, Gogin explained to Time Extension in a Twitter/X exchange that inspiration struck after experiencing Fez on the PC: "The idea came to me two years ago.

Although I was already working on other projects, this concept felt fresh.

I wanted to try something similar to Fez on the ZX Spectrum—not as a clone, but as a game in the same spirit." Relying on the graphics rendering experience gained during his 2021 project, Nothing, Gogin faced the core challenge: determining if the ZX Spectrum’s limited hardware could support such an ambitious vision. Development began in March 2025 with a prototype engine coded in C#, which was subsequently ported to assembly language.

The entire process, from the first line of code to the finished product, spanned 4.5 months.

According to Gogin, the 3D effect in Cubix is achieved by manipulating 2D tiles to simulate depth, rather than rendering true three-dimensional visuals.

"Three large tables manage the graphics: a tile grid for '3D' tiles and rotation, a coordinate grid for displaying sprites, and a precise table for calculating the exact placement of objects on the screen," Gogin stated.

These tables pre-calculate as much information as possible in advance, optimizing for the ZX Spectrum’s notoriously tight memory constraints. Elaborating further, Gogin noted, "On the classic ZX Spectrum, only the upper 16 KB memory bank can be switched.

This demanded highly efficient code and strategic memory use so that all rendering data was immediately accessible during play." By the time Cubix renders an image, nearly the entire processor address space is committed, with roughly 16 KB dedicated to rendering procedures, 24 KB for optimization tables, and 8 KB for graphics. Cubix is now available for download via the official YRGB 2025 website.

The game is playable on both emulators and original hardware, such as the ZX Spectrum 128K, offering retro enthusiasts and curious gamers an opportunity to experience this technical marvel firsthand.

With Cubix, Gogin has demonstrated that the limits of the ZX Spectrum are still being challenged decades after its release, making this a landmark achievement in homebrew game development.

ZX Spectrum platformer developer