Melvor Idle

I've brushed over this multiple times, dismissing it as a mobile game. That was a mistake! Although I initially found it hard to get into, they've since added a tutorial to explain basic mechanics - and if you can get over the UI being a bit unintuitive, there's a great game to be found underneath. The term "Idle" does it a disservice I think - it's actually quite a deep game with lots of interconnecting systems, and very satisfying whether you're playing actively, or a few minutes a day. It's not "incremental" where progress is exponential; they get boring quickly. At it's core - you are an MMO character gaining skills and resources, but the interface is just the UI.

Pros

There are loads of different skills to level up
Within each skill are items or subskills, which all have their own mastery level (so you might be 99 at woodcutting, but only 14 mastery in redwood trees)
All of the skills in the game are interconnected somehow. Woodcutting gives you fuel for Firemaking, which provides coal for smithing, for example.
It starts simply, and opens up quickly to be much more complicated than it initially seems
There are hundreds of different items in the game
It's not exponential - which is why most idle games get boring quickly; it's pretty much linear progression
You character has gear just like an MMO character
Gear items can be for combat or skill-focused
You can play actively and try to achieve small goals, or leave it running for a day to amass resources
Can be played on Steam, in a browser, on your phone or iPad all with cloud save
2 expansions released with lots of extra stuff (particularly enjoying cartography, which makes the game feel more like a real game and less like a spreadsheet)

Cons

There is no sound, at all. I understand not wanting skill sound effects, because a sound effect every 2 seconds would get annoying fast, but there should be UI sounds. It feels dead without that
Unless you manually turn on a different kind of level up notification, you aren't told what you unlock when you level up
Luckily there's a wiki, because there is zero information in the game about where to find things like specific enemies or items you need