Outdoor games for 4 year old party

[sponge]

We're having a joint birthday party for dd and a friend of hers and are planning it as an outdoor picnic.
Can you recommend any good outdoor, running arounbd type games - we want to take advantage of the space and lack of worry about mess to make it quite active.

Races - various themes such as hopping/walk like a penguin/slither like a snake/hop like a rabbit/roly poly etc
Musical bumps
Treasure hunt
Physical singing games - ring a roses/head shoulders knees and toes etc
Hope the weathers nice - if not, jumping in puddles and rolling in mud would go down well with my ds1&2

You could make a little assault course or obstacle race

Some of the ideas on this thread might be useful too.

Dd went to a 4th birthday party where they did races and had an obsticle course etc and loved it. And Woolies do packs of "medals", about £1.50 ish for a pack of several (vague I know!) and they had them as prizes. Its still on her pinboard now and she's nearly 7!

Here's one

Get all children to sit in circle. choose one person to be the bear. ( i think its a bear - I cant remember- i guess it can be whatever you like).
Put something noisy in front of bear, such as keys and everyone must shut eyes. You walk round the circle and tap one child on the head. they then have to get the keys and run round the circle back to their place without the bear catching them , - if theyre really quiet the bear wont even notice the keys are gone. bear is relaced by caught child.hours of fun. hth and you can understand what i mean , enjoy.