How to get my custom .desktop file into the unity launcher?
Did you try to write bash file for example just create a file and write this in
#!/bin/bash
cd dir_name; #the dir name to go
love-unstable mari0_1.0.love; #run the soft
then write in terminal chmod +x name_what_you_place
then you can just create a shortcut of that file.
Why not just associate .love files with the program love-unstable? Then you could double click on the mari0_1.0.love file and it would run the program.