Somewhat related to the topic (of Mao, not Nomic), one can build this kind of a "learn the rules while you play" event on top of
Sticheln.
Sticheln is a trick-taking game where you are always allowed to play any card. Hence you can never break the rules and the explanation "We play a trick-taking game where the winner of the trick always leads the next trick and the goal is to collect points, and before the game you place one (or two, depending on the variant) card in front of you" is sufficient for valid play. The guessing game is then in learning how tricks are won and how scoring works (at least one player naturally has to know these to moderate the game), and an observant gamer should be able to learn both after a few rounds.
The actual rules are simple but somewhat unusual for trick-taking games:
1) The trick is won by the highest non-zero value in any suit other than the lead suit (first one winning the ties), or the highest number of the lead suit if everyone followed. That is, all cards not matching the lead suit are trumps.
2) Every card won is plus one point, except for the cards matching the suit of the card placed in front of the player that score minus their number.
The 2nd rule is naturally very easy to learn if you announce points after every trick, so for a harder task they could be announced only at the end of the round.
The game itself is quite fun, and everyone who likes card games should own it since the deck comes with exceptionally large range of suits and card values, making it perfect for playing several other games that require numbered cards in several suits.