im honestly unsure for this. this initially seems like a fat no, but when you read the alpha section, there's nothing that really rules this out...
i honestly think this should be legal, unless the host says otherwise.
(so long as the tile fi are the same palette as the normal one, with the alpha being applied at runtime)
in the rules it says:
You can not use alpha in your art files, but you are allowed to change the alpha when the game is running to create effects like fades, trails and ghosts.
it doesn’t mention rendering sprites there, so it’s kind of up to interpretation. personally, i think this goes against the idea of the jam being 1-bit because it creates more than 2 colors on the screen at a time. if i were running the jam, i would not have added the allowance of alpha at an engine level. but do what you want. i think the worse thing is that people will give you a lower rating for having too many colors in your game.
