Crowd Master Arcade

Crowd Master Arcade is a 3D arcade crowd runner packaged from the
repository Gradle build. The snap ships the runnable desktop jar,
bundled runtime assets, and a compact Java runtime built with jlink.

levels are put in $HOME/snap/crowd-master-arcade/common/.crowdmaster.

you can edit those level and add new ones with a simple text editor or with a code editor, for intellij idea ( community or ultimate) you can use a highlighting plugin found here ( https://github.com/alfu32/crowd-master-arcade/releases/download/1.5.5/crowd-master-arcade-level-intellij-plugin-1.5.5.zip ).

the 3d models themselves that are used are available in $HOME/snap/crowd-master-arcade/common/.crowdmaster/assets as obj files.

Those obj files can be referenced and used inside the level files.
Their source is in the file $HOME/snap/crowd-master-arcade/common/.crowdmaster/assets/default-set.octd.

Octd files can be edited with Octodraw ( https://snapcraft.io/octodraw ) which has an obj exporter that can be used to export selected models as obj files.