Garden advice

I have a yard at the back of my house which is concrete, I am thinking of putting down scaffolding planks so it is safer for my 5 yr old son to play in. Is there any ideas about how to make it a really nice space for him to be in. We have lived here for 5 years and he has never been able to play safely in the garden. It is only a small area...the width of the house and about 6ft depth. the rest of the garden is steps and concrete that we wouldn't let him venture into.

He is over sensitive to noise, but loves flashing lights and getting messy. I feels so sorry for him and the rest of the family as we cannot use the garden and it has been neglected. At the moment all the animals are in the yard which will be moved.... any advice appreciated! I don't have a lot of money though so summerhouses etc are out of the question !

Thanks

Sarah