Experimental osu! server for 2010 clients, running on ESP32. It's designed for the b1596 version of the game, but additionally other versions between b695 and b1719 are working to some extent.
This server is very experimental, it will probably never be production ready (why would you run a production server on a microcontroller anyways?)
Unfortunately old osu! clients don't have an equivalent to -devserver, and doing just DNS tricks won't work because the Bancho IP address is hardcoded.
However, you can connect to the server using Titanic! Hook which will properly patch the Bancho IP without modifying the client.
You have to add records to hosts file (or add these at your self-hosted DNS server) with osu and server subdomains pointing at your ESP32's IP, for example for domain espcho.local you would add osu.espcho.local and server.espcho.local.
Next, you'll follow the Titanic! Hook instructions. Launch the client using the Titanic! Hook executable at least once. Then open Titanic!.cfg in a text editor and edit ServerName option to point at your ESP32's local domain (espcho.local in this case). Once you start the game using Titanic.exe, the client should be connected to espcho. Note that Titanic! Hook does not tamper with your osu! executable, so you have to start it using the Titanic! Hook executable to connect to espcho.
This implementation implements osu!Direct by forwarding requests to Mino (catboy.best).
There are a few caveats though, like response from Mino not matching what b1596 expects, but simple searches do work.
Due to forced HTTPS on catboy.best domain and ESP32 not having up-to-date root certificates, you have to disable TLS certificates at your own risk by enabling CONFIG_ESP_TLS_INSECURE and CONFIG_ESP_TLS_SKIP_SERVER_CERT_VERIFY in your board's menuconfig.
These projects were extremely helpful when making espcho!
- Lekuruu/chio.py - in-depth implementation of every Bancho packet for every osu! version
- Lekuruu/bancho-documentation - some technical information about the Bancho protocol
- osuTitanic/deck - implementation of client API (
/web/endpoints) for every osu! version