I haven’t run many RPG systems, but I’ve had great success running The Witch is Dead by Grant Howitt as a party game. Because it’s one page of rules with a succinct objective, it’s easier to learn and more broadly appealing than most card games – my mom enjoyed it as much as my nephews.

If I were looking for a new one-page RPG, I’d be looking for a few highlights:

• A strong elevator pitch. A one-page RPG needs to communicate a lot of ideas in as few words as possible. The intro to the game needs to set the tone and stakes and create common expectations. Being genre-savvy can help with that; tell your players that they’ll be executing a bank heist under the nose of a dragon, and they immediately know what to do and what can go wrong.
• Rules of thumb, not rules of math. I’m sure there are some great crunchy one-page RPGs out there, but that’s not really playing to the medium’s strengths, in my opinion. In The Witch is Dead, the spells the players can cast are described as “little bits of hedge magic to help around the house,” which I really like. It communicates their power and capabilities faster and more comprehensively than saying that Mage Hand can exert 10 lbs of force and move 30 feet per round.
• Good DM tools. Ideally, a one-page RPG should be as easy for the DM to set up as it is for the players to learn. In The Witch is Dead, there are roll tables for the village, the enemy, and the plot twist, which I found very useful. Just as the elevator pitch for the game needs to kickstart the players’ imaginations, the setting needs to be a springboard for the DM.