I have prepared a 3 1/2 level sampler for the hack I'm currently working on, Frivolous Journey. I likely won't plan out an actual overworld until the hack is nearing completion, so I've quickly put up a linear map where you can access the levels in any order you want.
As a quick note, Featherweight Fort is only halfway done at the moment. I'll be working on the rest of the level later, as I'm not too sure on which direction to go with it yet (the second half for each castle/fortress will likely involve some sort of callback to previous levels on the same world).
Hope you enjoy it!
Huge thanks to bebn legg, Koopster and Heraga for playtesting and offering some really helpful feedback.