The best casual games like Viva Pinata are Slime Rancher 2, Stardew Valley and Ooblets. Below are 7, 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 Viva Pinata 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.
Creature husbandry with the same tinkering loop and the same bright tone.
The gentlest deep systems game there is, and endlessly replayable.
Farming plus creature collecting, in the same cheerful register.
Open-ended, no fail state, animals to look after.
If designing the space rather than the food chain was the appeal.
Genuinely strange creature-breeding systems under a cute surface.
The series that established the whole shape of this genre.
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 Viva Pinata that are not casual games, so they are not on this page:
The full list is on games like Viva Pinata — 9 picks, no genre filter.
Slime Rancher 2. Creature husbandry with the same tinkering loop and the same bright tone.
No. Viva Pinata released on the Xbox 360, 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 Viva Pinata 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.