The best casual games like Tetris are Tetris Effect: Connected, Puyo Puyo Tetris 2 and Lumines Remastered. Below are 8, each with the reason it is here — and, at the end, what filtering to casual costs you.
Filtering to casual means you want something you can put down. That is the whole definition, and it says nothing about how deep the game is.
What you get: A game that fits around a life. Short sessions, save anywhere, no penalty for a week away.
What made Tetris worth playing in the first place is covered on the full list. This page is the casual part of that answer, and only the casual part.
The same game made overwhelming — sound and light tied to every piece you drop.
For the competitive half, and the best way to learn versus play.
Block-dropping on a musical timeline, so the beat decides when things clear.
Nintendo's other falling-block game, and the one built around colour matching instead of shape.
If what you loved was a tiny rule set with an enormous ceiling.
Arrows, mice and cats — the same purity of rules, with four players.
Ninety-nine players, one board each, and the only battle royale anyone over forty enjoys.
Puzzle League under its original name — swap instead of drop, and deeper than it looks.
Momentum, sometimes. A game designed to be left is also a game that is easy to forget you were playing.
Specifically, these are strong answers for Tetris that are not casual games, so they are not on this page:
The full list is on games like Tetris — 12 picks, no genre filter.
Tetris Effect: Connected. The same game made overwhelming — sound and light tied to every piece you drop.
No. Tetris released on the Nintendo Game Boy, 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.
No. Several of the deepest games there are — Tetris, Balatro, Into the Breach — are playable in twenty-minute pieces, and some of the shallowest demand an entire evening.
Often the opposite. Many are built around daily timers and streaks, which means stopping does cost you — the one thing a casual game is not supposed to do.
By hand. Each pick was written for the full Tetris list first, on what the game actually does, and this page is the part of that list that is casual — 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 casual guide for where to start in the genre generally.