Hi, I had a 4th bday party for ds a couple of months ago. At home, cheap and cheerful, less than 10 kids. It was lovely! I'm sure you'll have a lovely time too.
I had planned various games - pass the parcel, musical statues, who's afraid of mr wolf-type-thing, pin the tail on the donkey, sleeping lions - I had it all planned out, knew what was going to happen when, etc (well, quite vaguely, but you know)...lists and lists... and...
it totally didn't happen. I'd kind of forgotten that some of the kids there were still 3 and not as mature as ds and they just weren't interested in musical statues - they just wanted to run about and play! You know how they get when they're all together!
I got to a point where I had to decide whether to get all schoolteachery and organise them or just let them get on with it - and I just let them get on with it.
Everyone had a lovely time, I am sure you will too! (You can always google party games - I think it's a good idea to have back-up plans in case they get bored / out-of-hand and need direction. And you can always play them with the kids at other times when they have friends over etc.)
Have fun,
indiemummy x