Recently, some tweaks for New Horizons compatibility and I think a bug fix for potential problems sent from scripts to Character messages. You do not need a new game. If you use the Itch client to manage Maelstrom, you don't have to install because if you launch the Itch client, it will synch up the new files. If you do not use the Itch client, just download Maelstrom to the directory you keep the Maelstrom app files.