The best indie games like Balatro are Slay the Spire, Luck be a Landlord and Dungeons and Degenerate Gamblers. Below are 9, each with the reason it is here — and, at the end, what filtering to indie costs you.
Filtering to indie means you want the answer a small team would give. It is usually the most interesting filter on this site, because small studios take the risks large ones cannot.
What you get: One strong idea, explored completely, at a price that makes trying it easy. Indies have no production to hide behind, so the design is exposed.
What made Balatro worth playing in the first place is covered on the full list. This page is the indie part of that answer, and only the indie part.
The deckbuilding roguelike everything since is measured against.
A slot machine as a synergy engine — the closest structural cousin.
Blackjack rebuilt as a roguelike, and very funny.
Deckbuilding with more moving parts and huge combo ceilings.
Pachinko plus deckbuilding, and the same one-more-run pull.
A card game that keeps changing what kind of card game it is.
Inventory as the build, and the synergies are the whole game.
The free content updates, if you have not played the newer jokers.
Same escalating-numbers pleasure, no cards involved.
Polish and scale, sometimes. A few of these are rough at the edges, and a big-budget pick will always look better doing the same thing.
The full list is on games like Balatro — 9 picks, no genre filter.
Slay the Spire. The deckbuilding roguelike everything since is measured against.
No. Balatro 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.
Self-published, or published without a large publisher's money. It says nothing about the size of the game, which is why a forty-hour metroidvania and a two-hour art piece sit under the same label.
Constraint. Without a budget to hide behind, one idea has to carry the whole thing — and a small team can commit to something risky that a large one would sand down.
By hand. Each pick was written for the full Balatro list first, on what the game actually does, and this page is the part of that list that is indie — 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 indie guide for where to start in the genre generally.