If you have somehow missed the theme announcement, then here are the details:

Definition itself (that might get helpful) can be found here, and here's the quote about it from the blog post:

You can use it to build a game about traveling in time – to the past, or to the future. Speed through the history of humanity. You can manipulate the time itself in your entry, or make one about fixing watches! It’s entirely up to you, take your time to think about an original idea if you want to score high in the Theme criterion. But don’t stress too much, it’s up to you how exactly are you gonna interpret it!

So, what do you think about it? Any cool ideas already?