40 years after its release, Sega's 1985 Master System port of the arcade classic Hang-On has just received a brand-new "enhanced" version, courtesy of a fan patch, published late last month.
The patch, which was developed by a three-person team, including chirinea (art, music, project direction), Maxim (hacking, code), and badcomputer (title screen art), was created for SMSPower's 2026 hacking competition, and introduces a whole bunch of changes to bring the experience closer to the arcade. This includes redrawing the motorcycle sprites to better match the arcade version, adding a way to record your high scores, and implementing in-game music — a feature missing from the 8-bit editions of the game.
It is compatible with the 1985 Japanese version of Hang-On and, according to the team, was developed with the side goal of updating the game without ever expanding the ROM size.
Writing on SMSPower, the team behind the project stated:
"As the original was very full, this was achieved with various space-saving measures - mainly recompressing all art with ZX0 compression, but also replacing some of the tilemaps and text used to draw the screens with compressed data. It was also possible to remove some space used by SFX (which now only use a single channel) and for computing the bike engine RPM (which was used only to control the engine sounds). Some other data was replaced with more space-efficient code."
"It was also necessary to fully disassemble and understand the music engine in order to modify it as needed (and to replace the music). The final music is longer and more complex than the original, so it takes more space."
As detailed in this description, "an online LLM was used occasionally during development to help write Python scripts and to answer questions about makefile syntax", but was not used for writing Z80 code or to generate art or music.
Here's a full list of what's changed:
- Redrawn splash screen
- Redrawn title screen with animation
- Now there is in-game music, with SFX
- All music has been rearranged and made more similar to the original arcade music, using the original game's music engine
- Redrawn motorcycle sprites, more similar to the original arcade art
- Opponents are different colours in each stage
- Redrawn background art
- Road and scenery colours changed
- Rearranged HUD to more closely match the arcade game
- Race start redrawn to be similar to the arcade game
- New checkpoint SFX and text
- Split times are shown at each checkpoint, with frame accuracy
- Motorcycle acceleration is now smoothly varying with speed
- High scores are saved to cartridges saves (where supported)
- The original game's easter egg has something new...
- There is a hidden sound test
If you want to give the project a try, you can download the patch here.