Create /home/user/.config/firejail/barony.x86_64.profile and put the following inside the file:


# Persistent global definitions
include globals.local

noblacklist ${HOME}/GOG Games
noblacklist ${HOME}/.barony

include disable-common.inc
include disable-devel.inc
include disable-interpreters.inc
include disable-passwdmgr.inc
include disable-programs.inc

mkdir ${HOME}/.barony
whitelist ${HOME}/.barony
whitelist ${HOME}/GOG Games
include whitelist-common.inc
include whitelist-var-common.inc

caps.drop all
machine-id
netfilter
#no3d
nodvd
nogroups
nonewprivs
noroot
#nosound
notv
nou2f
novideo
protocol unix,inet,inet6,netlink
seccomp
shell none

# private-bin
private-dev
# private-lib - problems on Arch
private-tmp

# memory-deny-write-execute
noexec /tmp



Then edit the launcher so that it runs this:

firejail --profile=~/.config/firejail/barony.x86_64.profile "/home/user/GOG Games/Barony Blessed Addition/start.sh" ""

Replace "user" with your username.