The best family games like Human Fall Flat 2 are It Takes Two, Portal 2 and Unravel Two. Below are 7, each with the reason it is here — and, at the end, what filtering to family costs you.
Filtering to family means the game has to work for a child and an adult at the same table without either of them being bored. That is a much harder design problem than a difficulty slider.
What you get: Something you can put in front of anyone. The best family games make the skill gap not matter rather than pretending it is not there.
What made Human Fall Flat 2 worth playing in the first place is covered on the full list. This page is the family part of that answer, and only the family part.
The best two-player game there is, and every chapter is a new idea.
Co-op puzzling at its sharpest, if you want the puzzles taken seriously.
Physics, yarn, and a rope you both hang off.
If the flailing rather than the puzzling was the appeal.
Co-op physics chaos with a timer and a removal van.
Puzzles solved by throwing things, with a rewind for when it goes wrong.
Floaty physics platforming built for four people to laugh at.
Edge. Family games rarely go anywhere uncomfortable, and a few of them are too generous to hold an experienced player for long alone.
Specifically, these are strong answers for Human Fall Flat 2 that are not family games, so they are not on this page:
The full list is on games like Human Fall Flat 2 — 9 picks, no genre filter.
It Takes Two. The best two-player game there is, and every chapter is a new idea.
No. Human Fall Flat 2 released on the PC & Modern Multi-Platform, but a recommendation is only useful if you can play it, so the picks above span platforms and eras. What they share is the genre and the reason.
Age ratings cover content but not difficulty or frustration, which is what actually ruins a family session. Five minutes of unedited play footage tells you more than any rating.
With mixed ages, co-operative usually wins. The competitive ones that work are the ones where being in last place is still entertaining.
By hand. Each pick was written for the full Human Fall Flat 2 list first, on what the game actually does, and this page is the part of that list that is family — never a genre tag lookup, which is how "best racing games like Super Mario 64" used to be a page on this site.
Or read the family guide for where to start in the genre generally.