about 5 years ago - Sleipnir - Direct link
STEAM:
Note: Backwards compatibility is not guaranteed for old saves loading in new beta versions.
1. From the left panel on the Library>Games page in Steam, right-click Odd Realm.
2. From the drop-down menu, select Properties.
3. Select the top tab Betas.
4. From the drop-menu, select beta - Public test branch.
5. You won't need an access code, just close the pop-up window.
6. (Sometimes) You may need to exit and restart Steam.

The client should start downloading the beta branch build.

ITCH.IO:
The beta build on itch is just another file with '_BETA' appended to it. If you want to download that file of the game instead of the regular one, follow these steps.
1. Open the itch app.
2. Select Odd Realm from your library.
3. Click the gear button beside 'launch'.
4. You'll see a list of available files to install. Select the one for your operating system that says, '_BETA'.
over 4 years ago - Sleipnir - Direct link
You don't see this?

https://imgur.com/innG1qb
over 4 years ago - Sleipnir - Direct link
Check out the News page for that info:
https://steamcommunity.com/app/688060/allnews/