Frequently Asked Questions
Here are some of the most common questions about MD Engine.
Is there a macOS version?
Yes. MD Engine is available on macOS. You can also export your games as macOS application bundles (.app). See Exporting the Game for details.
macOS exports have not yet gone through Apple certification (App Store review). They are suitable for development and testing.
Can I export to mobile platforms?
Yes. MD Engine supports iOS and Android exports. iOS requires macOS with Xcode to build. Android produces an APK suitable for sideloading or distribution. See Exporting the Game for configuration details.
Mobile exports have not yet gone through Apple App Store or Google Play certification.
Can I export to handheld Linux devices?
Yes. MD Engine can produce PortMaster packages for handheld Linux gaming devices such as Anbernic, Miyoo, and others. See PortMaster Export for details.
PortMaster support is experimental. The packaging format may change in future versions.
Will it support [new platform]?
MD Engine is 100% focused on generating Sega Mega Drive-compatible games, so we don't have plans to include any other retro console platforms in it. That said, we may be working on other retro engines! So it's best to check our website to know exactly what we're up to!
Will it support Sega CD / Sega 32x?
Right now, the focus is on the base system. The custom PCB we use allows for 8MB of unmapped access by disabling access to the Sega CD, so that's one of the reasons we are not focusing on the Sega CD.
If you want extra features, we recommend you export the project and use the generated source code with your preferred toolchain.
That said, we may add support for those later.
Can I sell games made with MD Engine?
Yes. Games you create with MD Engine are yours. You are free to distribute and sell them however you like, including as physical cartridges or digital downloads.
Can I run my game on real hardware?
Yes. MD Engine produces standard Mega Drive ROMs that work on real hardware. You can use a flash cart (such as an Everdrive or Mega Everdrive) or produce physical cartridges using the Two Black Cats custom PCB.
My game runs slowly / the CPU load is high
Open the Debugger and check the CPU Profiler tab. It shows exactly where CPU time is being spent. Common causes of high CPU load include:
- Too many actors with collision checks — try the Gridding collision mode or reduce the number of active actors.
- Complex scripts running every frame — add Idle or Wait events inside loops.
- Large pathfinding searches — use non-blocking mode and adjust the Budget setting.
My game doesn't build / I get a build error
Check the Build Log for the specific error. Common issues include:
- Too many unique tiles — Reduce the number of unique tiles in the scene or increase the VDP tile limit in Settings.
- Too many actors or sprites — Reduce the number of actors or sprite tiles in the scene.
- Invalid event inside HBlank/VBlank — Only specific events are allowed inside blank scripts.
How do I save and load game data?
Use the save data events. See the Save System documentation and the Save Data Event Glossary for details. There is also a Save Demo template.
How large can my ROM be?
The standard Mega Drive supports ROMs up to 4MB (32Mbit). With the Two Black Cats custom PCB, sizes up to 8MB are supported. You can monitor ROM usage in the Build Log.
Where can I find example projects?
MD Engine ships with several Templates & Demos covering platformers, top-down action, shooters, and individual feature examples. These are the best starting point for learning how the engine works.