I see that the current version of the game is 32-bit. Do you plan to release it in 64-bit? I'd rather avoid using a lot of multilib stuff for it. There should be no good reason to release games in 32-bit today in general. 99.9% of Linux users are already on 64-bit hardware, and especially in case of gaming.
We've always used the 32bit build to develop the game and Unity has some weird differences when switching to 64bit. The risk is way too high to switch. E.g., in the past, switching cause certain physic-components to behave differently. As the gameplay has to be "pixel perfect" we made the decision to stay with 32 bit, which generally was much more stable when we made the decision.
I see. But going forward, please try to sort out 64-bit issues and switch to it. If you notice such bugs, please report them to Unity so they could fix them.
Releasing games in 32-bit only is becoming increasingly obsolete. Besides, there are common bugs (like forgetting enabling Large File Support for 32-bit build, and games failing in result on large XFS partitions) which many developers who are newcomers to Linux aren't aware of.
Even recent Unity games can be hit by it. Example: https://forum.paradoxplaza.com/forum/index.php?threads/bug-linux-tyranny-fails-on-large-xfs-partition.982757