This is interesting. gtk-launch have never been mentioned in this forum. So, here's what I found:
You can use /bin/gtk-launch + .desktop, instead of /bin/bash + .sh. I'm gonna assume .sh is like .bat. I like .desktop more because you can just double click it, just like a windows shortcut.
So, here's my settings.
Emulator Name dosbox
Executable /bin/gtk-launch
command arguments "[name]"
rom path(s) /home/even more directories/launcher folder
rom extension(s) .desktop
Non-blocking Mode Wait 1
This is the command of the launcher
dosbox "/home/even more directories/game folder/game.exe"
I don't know how non-blocking mode really works. But without it, the game only runs if I ALT+TAB. Maybe it's better to give it more seconds, I don't know.
Also, if you create a new launcher, Linux Mint will ask if you want to add it to the menu. You need to add it to the menu for gtk-launch to see it. I like it this way because it makes the games kind of like actual linux games. This might be a bad idea for other people. But I'm only planning to install old RTS games in this machine, so it works for me. If that ever change in the future, I'll switch to /bin/bash + .sh.