Which version of Unity does the game use?

As of 2023-10-13, Unturned uses 2021.3.29f1 LTS.

You can double-check the version in the game's log file by opening it in a text editor and searching for "Engine version:". (Ctrl+F in most editors) This line should be near the top. For example:

[2023-01-30 09:09:23] Game version: 3.23.1.2 Engine version: 2020.3.38f1