Progress! Here's an example of importing a tilemap with a a user-created image/tileset. The import includes some lighting objects as well, all thrown in to test the data storage. I had to recreate the light effect system so that the player will see the exact same lighting effects in this edit mode as will be seen in the main game...
Basic game-save and import logic
Image generation and save system (but needs tweaking to remove artifacts in corner cases)
Lots to do over the next couple of weeks, including:
Password protection for data
Data obfuscation system
Import saved level into main game
Long term objectives:
Create a bespoke platform behaviour. Sounds crazy but the default platform behaviour is not truly framerate independent and it makes wall climb / wall jump / multiplayer just that much harder to work out. I don't want to spend the next 6 months creating my own behaviour, but if this goes to plan then I will use it and the multiplayer plugin to properly manage collision detection v latency. I'm going to run this in parallel to the main game dev, so I can swap between the two when I get bored, so it might come to nothing.... .