One similar self-hosted solution is https://gotify.net/ , which also has Android and web apps and a similarly simple way to push messages using curl/http.
6 karma · joined December 12, 2019
https://www.lexaloffle.com/pico-8.php
If you want to make an adventure game, you can make a hypercard-like text game in Twine which also exports to the web. You could even draw on old DOS fonts like at https://int10h.org/oldschool-pc-fonts/fontlist/ and style your game like it's 1990!