They were pretending, playing, not indoctrinating. Can't you see a difference between a game intended to teach people about something and requiring or encouraging a prayer which a majority of the class actually thinks that they believe?
I know when I was required to recite the Lord's Prayer as a child, I was uncomfortable. this was a Christian prayer and I was Jewish, I didn't want to say it. The teacher sent me to the principal's office for not reciting it, even though I did nothing to actually disrupt other people reciting it, I just stood there mute, looking down. Fortunately for me, the principal sided with me not the teacher. This was about the time of the Murray decision, though slightly before it. The teacher disliked me from that point on. No pressure? No consequences?