This game makes clear that divergent and convergent phases are both useful, but that some people feel more comfortable in one or the other and that they should best be separated.
Participants will keep referring to this warm-up during (and even after) the project. Do it before important group work sessions, especially sequential ideation methods like 10 plus 10. For more impact, let the participants do some group work before the warm-up, then some afterwards – and compare the difference.