Every mobile is installed with games. Different types of games are installed in different models of mobiles. Every manufacturer installs different types of games in different types of models of same company. If you are bored with the pre-loaded company games then download third party games. There are many websites out there which offers you free games to download either via WAP service or download to your https://www.learn-basics.com/computer and transfer it with the help of data cable or bluetooth dongle.
One such website I found is http://gallery.mobile9.com/ here you can download any or all mobile games, Java games, software, ringtones and many more.