I usually do parties at home, with variations on traditional party games and about 10-15 kids.
but by age 8 they are getting a bit big for that.
at 8 ds had a football in the dark, dvd , pizza and sleepover. Sleepover was a mistake.
dd1 had Great British Bake Off with 8 kids in teams of 2 and cooking, cupcake decorating, competition and tea. That was a good one.
at 9 she had a spies party with a spy school for activities which was good too.
dd2 will be 8 soon. I need a party idea that will allow us to have it at home (budget tight) but be different to traditional kids party, so I can come up with games or activities that will keep about 10 kids going for a couple of hours. Cannot involve any buy in entertainment, but I am game for quite a lot 
I am idealess, and so is she, Birthday is Nov, so we have had treasure hunt in the garden before now, but mostly inside.