Everyone knows how to play Uno. Everyone thinks it's lame, but then they always end up having fun when they play and get to screw their buddies with the 'skip' or 'draw 2' cards.
I'd be shocked to encounter a teenager who knows how to play yahtzee / euchre / cribbage / etc. (I'm a Hold 'Em man, myself.)
You need a sucker for snipe hunting. And it is best if they have a sense of humor. I can't see teenagers getting excited about a scavenger hunt- tweens or younger, maybe, but not teenagers.
Any of those card games that have been all the rage for the past couple of decades would work, too. Being an old coot, I've never played 'Magic:The Gathering', but I've played 'San Juan' and 'Munchkin', and I think they're fun. Both are rather complex, though, with a steep learning curve.
Also, everyone adult and teenager thinks a hacky-sack is fun for a limited time at least, but you need light. Also not fun in the rain. We take hacky-sacks to kill time on deployments or field exercises. (I'm in the army.)
On that subject, the card games popular in the army are Spades or Hearts. Hearts has the added benefit that you can screw your buddies, again. Always fun. Hearts is also easier to learn to play well than Spades.
Likewise a frisbee, or one of the packable/foldable versions thereof. Just tossing a frisbee back and forth gets old quick, but frisbee golf is entertaining for a while. But best with >1 frisbee. Also not good in the rain.