If you are thinking of open sourcing, it can still be a good idea because users will pay for the convenience of not having to compile/build themselves.
I also think that very few people would get any benefit from being open-sourced since it depends on modified Unreal Engine - the project itself and the engine mean that the git repo is over 100GB even when shallow cloned. I could open source the core game systems but they’re almost entirely useless without the rest of everything.
Edit: just thinking of it, I wouldn't be able to distribute the modified UE source either - it's source-available but you need to agree to Epic's licence to get access. Might be possible to only distribute a diff and instructions on which version of the engine to apply it to? In any case it would be a lot of work.
But another developer could republish the game for half the price, no?
Depends on your license, you can be open source but have a license prohibiting assets usage or even whole code usage. It can be a good way to support mods.
See Barotrauma [0][1] as an example of an open source game that suceeded.
Exerpt from their license :
> The source code, modifications or derivative works can be distributed only if they are intended to be used as a mod for Barotrauma. You are not allowed to create a standalone application, or use the code for commercial purposes or in your own projects. You are not allowed to remove or bypass Steam integration, SteamID authentication or any other DRM measures from the code.