If you need a bright, colourful game that doesn't require a lot of brainpower but gives you shinies (and that is not a gacha game) but just keeps you occupied for a bit, I have a recommendation for you!
In Vivid Knight, you play as a mischievous princess whose subjects have been turned into gems by an evil with, and so you go dungeon crawling with your restored subjects. (there is also a mode that lets you play as the with but I have not unlocked that yet)
it is a very cute dungeon crawler where your very cute party members fight automatically on their own, but you can throw in some abilities from the princess sometimes, and of course decide where to go in the dungeon
and you collect party members and abilities at random and can add more to the pool permanently through what is essentially a gacha system with in-game currency. (there are no microtransactions)
there's really no plot or lore beyond the set-up, but if you just want some candy for the part of your brain that likes to click on shiny things and watches numbers go up and stuff, well.... there you go.
the main downside is that it's only on steam, when it would be such a good fit for phones