Sonic the Hedgehog on Amiga AGA takes shape with Aonic Green Hill Zone demo

Aonic has reached a point where it’s no longer just a technical experiment. The latest build now offers a playable version of Green Hill Zone on PAL Amiga systems with the AGA chipset and 2 MB of Chip RAM. That changes things. Instead of looking at screenshots, scrolling tests or isolated engine demos, Amiga users can now see how the project behaves as an actual game. Sonic runs, jumps and moves through Green Hill Zone while the engine handles the level around him. The demo is available in early access, with a wider public release planned for 31 August 2026.

Bringing Sonic to very different hardware

Sonic the Hedgehog launched on the Sega Mega Drive in 1991 and quickly became one of the system’s defining games. Its speed was a big part of that, but the game also depended heavily on the Mega Drive’s graphics hardware. Green Hill Zone throws plenty at the machine. There’s fast scrolling, changing terrain, animated scenery, rings, enemies, slopes and several layers of graphics moving at once.

The Amiga can handle impressive visuals too, but it works very differently. That’s where Aonic gets interesting. The project uses original Mega Drive code and game data as a starting point. That means the level layouts and much of the underlying behaviour can stay close to the Sega version. But the graphics routines can’t simply be copied across. Both machines use Motorola 68000-family processors, which helps, but their graphics systems have little in common.

How Aonic handles the graphics

The current AGA engine uses five bitplanes for the foreground graphics and converted Mega Drive sprites. Together, they provide a shared palette of 32 colours. The background takes a different route.

Aonic uses attached AGA sprites for that layer, giving it a separate 16-colour palette. Earlier versions experimented with dual-playfield graphics, but that approach used all eight bitplanes and placed tighter limits on colours and memory bandwidth. The newer setup gives the engine more room to work.

It also means Green Hill Zone doesn’t have to be drawn exactly the way the Mega Drive draws it. The final scene can look familiar while the Amiga builds that scene using completely different techniques underneath. That’s really the heart of the project.

Green Hill Zone is more than a graphics demo

The engine doesn’t redraw the whole level every frame. Instead, it caches sections of the stage and updates graphics as new parts of the level scroll onto the screen. The Amiga’s blitter handles a lot of the graphics work.

Original Mega Drive tiles also need converting into the Amiga’s five-bitplane format. Flowers, waterfalls, foreground details and other animated parts of Green Hill Zone all have to fit into that system. It’s not just about getting the picture right. Sonic’s movement matters just as much.

Sonic still needs to feel like Sonic

The original game relies on a lot of movement code behind the scenes. Acceleration, rolling, slopes, curved surfaces and collision all affect how Sonic responds. Get those wrong and the game might look like Sonic, but it won’t feel like Sonic.

Aonic keeps and adapts much of that behaviour from the Mega Drive codebase. That gives the Amiga version a much stronger link to the original game than a simple visual recreation would. The development tools have changed too.

Tile-conversion software now prepares Sonic graphics for the Amiga engine, while the Mega Drive game’s demo-recording system has been adapted so playthroughs can be saved to disk. That’s useful for testing. Developers can replay the same section of gameplay again and again, making it easier to measure performance and spot slow areas without relying on slightly different manual runs each time.

Designed for a standard AGA Amiga

The current target is straightforward: a PAL AGA Amiga with 2 MB of Chip RAM. That puts a standard Amiga 1200 within the intended hardware specification. You shouldn’t need an accelerator just to run the demo.

For now, the focus is the first level and the systems required to make it work properly. Scrolling, graphics, collision, sprites and player movement are all part of the current build. Audio isn’t the main focus yet. There’s also a lot more of Sonic the Hedgehog still to cover if the project moves beyond Green Hill Zone.

Aonic is still a work in progress

This isn’t a finished Amiga version of Sonic the Hedgehog, and it doesn’t pretend to be one. What it does provide is a working AGA engine running an actual Sonic level rather than a small technical test. That makes it much easier to see what the project can already handle and where more work is needed.

The current plan puts AGA first. An OCS version may come later, but the immediate job is getting the engine working well on Commodore’s later Amiga chipset. For Amiga owners, the most interesting part is simple.

Green Hill Zone now runs as a playable game on AGA hardware. The engine is there, Sonic is moving through the level, and the project has crossed from demonstration code into something you can actually play.

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