do we own the games? the organisation i am working with for my school project want full rights, do we need to buy?

You have all rights according to the Creative Commons License as long as you do not use anything alredy trademarked. If you want to sell your game, you should give credit to everything you used and should make sure nothing you are using is already trademarked. So in essence, yes, you have full project rights, but don’t infringe on the trademarks.

And Grazer also said there is no need to credit him or Flowlab if don’t want to.
Anything you make here is your property and idea with under the Creative Commons License.
But like @meburningslime said, the license protect other trademarks or games from infringement.