I played as at summer camp, in the late 90s, so jacks has NOT yet gone out of style. We played with 10 jacks. we did onesies up to 10, and we played with strict rules, no moving any other jacks, no horse before carriage (such as, picking up the 2 before the 8 on eightsies, etc.), and even no moving your butt off the ground. After tensies was a level called lollipop, and then we had to descend down from 10. After that we did 3 tricksies (such as cherries in a basket, cracking the egg, no bouncies, double bounce, squeezing the lemon, etc.), and then 3 flipsies in a row without dropping anything. The person who finished first was the winner. One girl in my bunk was amazing, I remember she once did it all in one turn.
My whole bunk was obsessed with jacks. We would play it everywhere and anywhere we could.
When I worked as a counselor, I would teach it to my campers and they loved it too. It is definitely a timeless game.