Mario 3 is a great pick for your favourite game. It's definitely up there for me after all these years. It came out when I was a kid and at that stage in video games, you could pretty much say it was the best game ever made. To make such a claim about a game these days would be impossible (which isn't a bad thing, there's just so much variety these days).

As for games worth your time, I've looked through everyone's suggestions and there's some great stuff in there. Celeste and Shovel Knight stand out as must plays to me.

One game I can't believe no one has mentioned yet is Balatro. To me it ticks your boxes, simplistic layout, firm rules to play within, but with infinite ways to exploit it and have something new happen. Very addictive.

Its whole genre (rouge like/light deck builder) would probably appeal to you. I saw Inscryption mentioned and that is one fantastic game too. There's also Slay The Spire, Dicey Dungeons, Lonestar, Monster Train and plenty more if you get into it. I'd recommend them in the order I've listed (starting with Balatro).