Guys whats the theme of this game jam? Can I use Unity for making game?

I don't know the theme, but I do believe you are allowed to use anything. WinForms, Unity, Unreal, whatever. However, before you do that, you may want to check the rules. Good Luck!

With Game Jams, the theme is generally announced right at the start.

The theme will be announced at the start of the jam.