Hey Richard! Many thanks for your contributions over the years; way back to the "simulate NTSC artefacts" feature which iirc I pitched for Genesis/MegaDrive before I even knew much of anything about emulation and video standards, and which showed up in EE some arbitrary time later even though initially it seemed kinda lame to you.
I may still re-register anyway (although I must say, OpenEmu is pretty slick...), but I would
absolutely be willing to throw double or triple the usual registration fee to get one very probably simple feature either in Oswan or EE:
screen rotation.
Literally, just take the game's usual render buffer and rather than blitting pixels between pixels to make the final window content bigger, just pop the whole thing in a 90-degrees-left transformation matrix to make the final window content sideways.
Even on perfect emulation, games like Magical Drop, Beatmania, and portions of Rockman & Forte are not practically playable because they rely upon the WonderSwan's unique gimmick of turning the unit 90 degrees counterclockwise.
If you literally do not have a machine that can build the code anymore, I totally understand (I'm running into that problem myself with a few older projects these days). But if you do, there's still that one small emulation-quality never-been-done-before (to my knowledge...) achievement to unlock
Also, were you party to any of the original Oswan dev docs, or did you mainly just poke at the code until it built on Mac? I've found some fairly complete tech/homebrew docs for WS, but they have s few holes specifically in the sound system which, based on the state of emulation, I've got to believe someone somewhere must know.