If a student does not seem to know what is going on, I comment on that and remark that I'll start with him first at the next meeting. Keep notes on student involvement and follow through. The individual questioning puts a student on notice that he must be prepared and it also avoids domination of the meeting by the most controlling students. Most games allow you to start completely over after the trial run. Set regular times for turning in decisions and returning output.
Some games require a posting of results.
If no results are posted, put a dated announcement on your office door of when output is available. Meet with each group at least twice during the term. You may be able to meet with several non-competing teams at once. The meetings are important to clear up misunderstandings about rules, to plot strategy, and to monitor team member involvement. During lecture, draw parallels between the game and the textbook material you are covering.