My 15th Birthday Party

Hello i need to plan a amazing birthday party for girls and boys of age 15-18. It will be on the 10th june in the garden and kitchin at about 6:30 till 9:30. Im having a sleepover too afterwards with the lasses. Ive got ideas for the sleepover just not that many for the attual party!... Sofar im havin games such as twister. Music and dancing. Food. Jelly and ice-cream. Fancy dress. But i feel i need more to fill up the time so people dont get bored. Help me quick please x