Stephen, it's Clem Fandango. Can you hear me?
YES I can hear you Clem Fandango!
Age = range. Prolly youngest 5 or 6 oldest 12 / 13. Ish :-P
Number: max about 30. Prolly about 20-25.
see if you can get a copy of Captain Clueless: Lost in the Caribbean it's a team 'draw a route while blindfolded' game that could at a stretch do 20 in 4 teams of 5. (I looked to see if I could lend you my copy but a 3 hour car and plane journey and a $1000 of tickets rules it out.)
You might try werewolf- maybe changing it to wizards. the issue will be kids peeking.