i don't know how far can we propose a list of them:
- hydrogen
- easytoon
- multipaint (zx-spectrum (zxpaintbrush could be another alternative), c64, tms9918 mode 2 (msx, colecovision, sg1000,ti994a, etc.) )
- cgedit (sharp mz700)
- nodebox/shoebot
- processing.js
- rexpaint
etc..
(and there are some interesting editors for zx-81, c64 petscii, etc., that could be added as well )

edit: .ttf/.otf battles would be great as well! (perhaps only for majors for starting, perhaps 4hb is too tight time limit for starters...)

hey, i think processing is a really cool format idea. i would love to see more coding related formats in general.

@Trreck and talking about coding, i don't know if you know this one, perhaps you might enjoy: https://msxpen.com/ (try to code something there, in msxbasic syntax, and click on the share button! ;) )

i don't know about most of those, but processing js could just be hosted as html5 ohb.

I don't think we should have multiple graphics formats specific to some software. if it's raster then pixel/draw/allgear, if it's vector then svg. visuall works for gif animation if that's something that easytoon supports.

hydrogen: i'm guessing this is the drum software? not sure if it has any melodic sequencing. the h2song format is saves to appears to be an XML file that only stores sequencing and doesn't store samples. if it doesn't have a portable file format then it can't practically be a format on botb.

rexpaint: ascii and ansi are already formats

nodebox looks kinda interesting though, I might try it out at some point

^
i would say nodebox and maybe processing.js are viable, but that's about it.

as someone who has used nodebox a lot before, it is an absolute bitch to use and i fucking hate it. if it gets added as a format i will eat the sun