creating build on remote server: itch.io API error (400): /wharf/builds: invalid game
Often times this means you're logged into a different itch.io account; this happens to me moving between my personal account and the one I publish to. Try running ".dragonruby/itchio-butler/butler logout" in the directory where you ran dragonruby-publish, and then try publishing again, where it will prompt you to auth with itch.io again.
The other reason you'll see this error is if your username or the gamename is wrong in the metadata. If the game is publishing to, for example, https://dragonruby.itch.io/flappydragon , then your devid should be dragonruby and the gameid is flappydragon.
Also, if you haven't actually created the game page on itch.io at all yet, do that first.