The rules state that the game must be created "from scratch". However, the email I received announcing the jam states:

"I will announce the theme once the jam begins and then you have up to 48 hours to create a game from scratch using any assets you can find."

So, are purchased assets allowed? What, exactly, is meant by "from scratch"?

I'd say it means that you're not allowed to submit a game that you started creating before the jam start.. or an already completed game.

You can use assets.. but you have to create the game during jam time from start to finish.. as it usually is with jams.

I'll leave it to the host to leave a clearer answer tho :)

The project needs to be from scratch but you can use any assets.