Playing a Game/role-playing

My son has trouble getting along with his siblings during "free play" times at home. His older brother often comes up with a game for them to play together and they start out okay, but soon ASD-son is yelling or crying. A recurring refrain is "That's not fair!"
He often either doesn't seem to understand the rules or doesn't like it when he loses and so claims "not fair" or cries and has a tantrum.
I wrote out the below sequence of strategies to help him and then I read it and role-played it out with him and his two siblings. It went pretty well. We'll see if things go better over the next few weeks! : )
P.S. We have learned what "negotiating" and "being a good sport" means previously.

Playing a game

1. Find out the rules. Ask questions.

2. Decide if you can play by the rules.
A. If you don’t like the rules or can’t play by them, negotiate to see if you can get everyone to agree on different rules.
B. Or say that you will not play because you cannot play by those rules.

If you don’t play:
3. Stay out of the way if you decide not to play.
A. If everyone else plays anyway you can watch or do something else. You should not yell or fuss at those choosing to play the game.
B. If someone asks you to play anyway, you can change your mind and say “Ok, I’ll try to play.”
Or you can calmly and clearly say, “No, I don’t like the rules of that game. I’m not going to play.”
4. If someone yells at you or calls you names for not playing you should not yell back. Don’t say anything and continue what you are doing or go be with someone else who can help you.

5. .If someone hits you or throws something at you go quickly and quietly to find an adult to help you. Tell them exactly what happened.
Like this, “I do not want to play their game. They are yelling at me and hurting me because I won’t play.”

6. The adult may suggest that you play their game. Tell the adult the reason you don’t want to play, including the rules you don’t like or can’t follow.

If you decide to play:
7. Do your best to play by the rules and to be a good sport whether you are winning or losing.

8. If the leader or someone else in the game decides to change the rules during the game, say, “Stop, time out. Why are you changing the rules?”

9. Then you have to decide if you want to play by the new rules or not play. Repeat steps 3 - 6.