The game works fine with Proton, but native is borked. So if you want to run it natively, some work is needed. It tries to launch the wrong executable ("Kindergarten2.x86_64" rather than "Kindergarten.x86_64"). Simply renaming the executable does not work. My solution was to write a short C program that simply launches the correct executable.

#include <stdlib.h>

int main()

{

system("./Kindergarten.x86_64");

}