Generally, the best options are ports of PC games. Things like Slay the Spire, Balatro, Mini Metro, Terraria, BaBa is You, or Stardew Valley. Not as cheap, but worth the price tag.

A couple of my favorite free options:

Unciv - Its an attempt at recreating Civ. It's got a lot of issues, such as lacking a lot of the more in-depth mechanics and having terrible world-gen, but its also free.

Vampire Survivors - a fairly simple but content-rich arcade game, reminiscent of old flash games.

Super Auto Pets - an autobattler like autochess but stripped down to its fundamentals making it easy to get in to, and easy to play in short bursts