Hello and Welcome to FixYa!
The format is
.jar (
As the phone renders the game on Java Platform), you can download free games from
this site, all you have to do is to download the games to your PC, connect the phone to the PC via Data Cable if you are on the PC Suite then just place the games files (
.jar, that you have downloaded from the website) in the
OTHER folder, and if you are on the mass storage mode, then again you just want to place all the game files in the
other folder, when done, remove the cable, and from the phone goto other folder, and you will see all the games there but they are not Installed yet, there will be the option to install there, it will automatically install and will ask you to put that game in Applications or Games folder, as you can also install Applications by following the same steps.
If you are having any issues/questions, do ask me, I'm here to help.
If you think I was of help, your token of appreciation in the form of rating will be esteemed.
Concerned, Nooh