Nice work!
The main (and practically only) reason I'm hesitant to use Ultra Engine right now is due to the lack of built-in multiplayer support and/or the lack of any examples or tutorials on how to get client-server or peer-to-peer networking implemented properly.
If you could get Steamworks API's networking features working (and maybe have an example or tutorial on how to set up client-server and peer-to-peer stuff working with it), then that would be amazing!