i just wanna know if i can make anything i want or i have to focus on a theme

There is no theme other than a few simple rules to follow for us to test your game and give feedbacks on the jam page. 

• Your game must not include any NSFW and offensive/discriminatory content 
• 1 game per team
• If you game is paid you must have free version available
• Host your game anywhere just submit an Itch page with the game links
• You may use any engine, framework, or assets that you have the proper license/permissions to do so (please give credit where necessary)
• The game is rated on the overall user experience
• Submitters maintain full ownership of their submissions to the Jams
• Please be respectful towards each other