Tun Kai Poh
Hero
Any game for no-prep casual play has to have very short rules (1-4 pages), and hybrid roleplaying/card games are great for this by providing rules, prompts and play structure on cards.
Like Fiasco:
bullypulpitgames.com
Or For The Queen:
www.evilhat.com
And in an act of pure self-promotion I'll drop in my micro-RPGs on itch. They're both very short, have very few mechanics, and require no prep.
roleoverplaydead.itch.io
roleoverplaydead.itch.io
Like Fiasco:

Fiasco
Fiasco is an award-winning, GM-less game for 3-5 players, designed to be played in a few hours with no preparation. During a game you engineer and play out stupid, disastrous situations, usually at the intersection of greed, fear, and lust. It’s like making your own Coen brothers movie, in about...

Or For The Queen:

For the Queen - Evil Hat Productions
The land you live in has been at war for as long as any of you have been alive.The queen is under attack. Will you defend her?

And in an act of pure self-promotion I'll drop in my micro-RPGs on itch. They're both very short, have very few mechanics, and require no prep.

ECH0 by Role Over Play Dead
Peace. Kids playing in mech wreckage. A ghost. One last journey to find a final resting place.


The Ech0 Consultation by Role Over Play Dead
2 doctors in 1 body. Complicated collaborations. Risky medicine.
