S.D.'s script to (almost) properly launch Unity3D games

#!/bin/sh
##
# 2012, S.D.
##
# S.D.'s script to (almost) properly launch Unity3D games

# Assign absolute path to the game binary to the GAME_BINARY variable
GAME_BINARY="/home/${USER}/bin/demos/Cornerstone/Linux_Build_2.3.x86_64"

if [ x"$GAME_BINARY" = x'' ]
then
    echo "Set GAME_BINARY to the game binary's absolute path in script '$0'"
    exit 1
else if [ ! -f "$GAME_BINARY" ]
then
    echo "GAME_BINARY is not set to the path to the game's binary"
    exit 1
else if [ ! -x "$GAME_BINARY" ]
then
    echo "GAME_BINARY is not executable;  fix permissions"
    exit 1
  fi
 fi
fi

# Move to script's directory
cd "`dirname $(realpath "$GAME_BINARY")`"

XWININFO_HEIGHT=$(xwininfo -root | grep Height | cut -d ' ' -f 4)
XWININFO_WIDTH=$(xwininfo -root | grep Width | cut -d ' ' -f 4)

exec ${GAME_BINARY} -screen-height $XWININFO_HEIGHT -screen-width $XWININFO_WIDTH