You don't need to self-host a Matrix server.
Just to be sure:
- Matrix server != Discord server
- Matrix Space/Community ~ Discord server
Matrix Spaces/Communities are handled inside a Matrix server.
You can pick just an existing one like the matrix.org one ( bundled by default when you access tohttps://app.element.io/ ) and create an Space/Community there which is equivalent to Discord servers.
Edited: hosted bridges for Matrix<->Discord already exist,https://t2bot.io could help with it.
I have already bridged successfully different rooms from Discord and Telegram.
This game is tagged as Open Source but it doesn't fit the Open Source definition itself trademarked by the OSI (Open Source Initiative) inhttps://opensource.org/osd as showed in the EULA at the beginning of the gameplay setting that this is propietary software, not Open Source.