That's what I've been asking myself since I read the criteria for selecting featured games. I'm talking about this, specifically:
Installation: +1 point if the game installs and uninstalls correctly
I wanted to add achivements to my game (like the ones in PS3/XBox games) and I thought about writing a text file and save the progress of the player and the amount of trophies earned in that file. But the thing is that that file would be created in the same directory as the .jar (or any other folder) and if you wish to delete the .jar then the savegame file will remain there (duh) unless you delete it as well. Then I thought that I could simply create a file or modify an existing one within the .jar, and update it while in game. A quick google search on how to do that made me realize that it was too difficult/impossible to do.
I could also use an installer and then the uninstall would take care of the problem of deleting the .jar and the savegame files for the user, but the question remains the same:
Is it possible to create a savegame feature in a game deployed trough an executable .jar while not creating extra files for that purpose?