I got this idea from a TedX talk by Chris Lonsdale: "How to learn any language in six months."(https://www.youtube.com/watch?v=d0yGdNEWdn0).
The concept is simple: create a simple 3x3x3 matrix of three nouns, three verbs and three adjectives. Make sentences using one of the nouns, one verb, and one adjective. The goal is to make as many meaningful combinations as possible.
The players should feel free to add other words and parts of speech, but the basis of the sentence should be three words from the matrix.