Hi M.,
Have you ever watched the Super Nanny show? She deals with this in families all the time and her method is the same with every family and it always works!
You do your routine, then say good night, lights out and close the door.
If your child comes out once- you say, it's time for bed (or your choice of words) and take them back. Tuck them in and close the door.
If they come out again- you DO NOT speak to them and carry them back to bed and close the door again.
You may have to do this for a few hours the first night, but I PROMISE you- if you are consistant- every night it will get less and by the 3rd or 4th night your son should be sleeping well- knowing he can't get attention anymore by coming out.
That is what kids are looking for- to be acknowledged and engaged (like you said- it is a game to him). So the no speaking thing is a HUGE part of the success rate of this practice.
If you have to carry or partially drag your child in tantrum (as I watched other parents have to do) that is alright. It will upset you to have them fighting you, or crying- but you have to be consistant.
So maybe start it on a weekend, when you know you can deal with less sleep.
First night- bed routine, lights out and close door.
First time child comes out- tell them it's bed time and put them back.
Second time they come out and every time after- NO SPEAKING, and continue to put your child back in bed.
I have seen this practice work time and time again. And usually the kids give in by the 3rd or 4th night much to the astonishment of parents. I was even shocked the first time I watched it.
The thing that feels scary is that it feels like it will go on forever, but the parents see the results within such a short few days that they keep up with it.
There is a Super Nanny book too that can talk you through this as well.
There will be lots of opinions on this, so I hope mine doesn't offend anyone- but I know this works, and with only a few short days of disruption/upset you will have the REWARD of children sleeping well and parents resting too.