The full saved kingdom is currently designed and tested around Codex with browser access and ChatGPT sign-in. Other browser agents may work, but I haven’t verified them, so I don’t want to promise compatibility.
There’s already a smaller browser-only option: on https://turnfeed.theodornengoy.chatgpt.site/ choose Kingdoms → Try a practice raid. Those exercises need neither an account nor Codex. They are separate from the full kingdom. I don’t have a release date to promise for a standalone, directly playable full-game version on itch.io.