Here’s one of mine:
Jenga Fortress
Split Jenga pieces equally and sit in a large circle (on the floor or at a big table). Everyone has one piece that is marked. Then everyone builds a fortress to protect their marked piece (the marked piece must be stood up on its small side).
Everyone gets a projectile. We liked using those thick rubber bands that came on broccoli at the grocery store, but you could use Nerf guns, balled up paper, whatever–as long as it’s not too light and not too heavy.
Once everyone is ready, take turns firing at each other’s fortresses, trying to knock down their marked pieces. Nobody can touch their fortress at this point.
Last marked piece standing is the winner.
“Hunter.” The play area is a big part of the neighborhood. The details were a little variable depending on different experiments or how many people were playing, but one canonical version is three hunters with walkie-talkies, trying to find two people without walkie-talkies, with a time limit. No other rules aside from don’t piss off any neighbor inside their house overly badly.
A good solo game for long car trips was looking out the window riding an imaginary motorcycle. You can go up on power lines if there’s a slanted wire you could ride up, you can move left or right, but if you box yourself into a place where you’ll hit a vertical wall no matter what you do, you crash.
Various hallucinogenic DND-but-not-really variants played with no sourcebooks, and a piece of paper with a grid with numbers that you flick your pencil eraser at with your eyes closed to “roll dice.”