Separate projects will mean different Master Banks which means different master buses. This means if you wish to use this setup you would need to unload one master bank (and all banks associated with it) and load a new master bank (and any necessary banks) in order to use that projects events. A snapshot from one project cannot affect any buses or events from another project.
You will need to merge these projects together into one project.
If you right click on an event and select “Copy” you can paste that event with all its associated assets into a different project. It will give you the option to create return buses for any sends in the pasted events but please note that it won’t generate any effects you had on that return bus so you will need to add those manually.
Pasting events from one project to another will not maintain that events folder structure, VCA assignment, or mixer routing so you will also have to manually do this too.
It would be best to always work in one project for one game to avoid these situations in the future.