I can also recommend Beyond all Reason.
If you ever played Supreme Commander, this game is like a sequel.
It also has an active YouTube streaming community with tutorials and ingame are some scenarios to teach you about the various units and strategies.
I'm not all that far in the game, but it seems progression revolves around crafting. Killing enemies and mining for materials to make various armours and weapons to take of harder dungeons.
I don't believe there are quests or pvp yet unfortunately, but it still ends up being fun despite being a highly ambitious game truthfully barely scraped the surface of its ambitions yet.
Endless Sky. The save game is a text file. Save a file on the mobile app (F-Droid), and on the PC (Flatpak), and note the last line. This is the line you must swap to transfer the save file. It is the first game I have played on both practically. The game mechanics are different between the two and you need to alter your strategy accordingly. On mobile, I travel with a ship setup for boarding pirate vessels and never target enemies directly; all of my guns are automatic turrets. I just use a fast ship and travel with a large group of fighters. It is more of a grind on mobile, but it can be used to build up resources and reserves. The game is much bigger than it first appears to be. You need to either check out a guide or explore very deep into the obscure pockets of the map.
I haven't seen OpenTTD mentioned yet: https://www.openttd.org/
If you like it you may also check out OpenRCT - although this one needs original game files from RollerCoasterTycoon (a few bucks on Gog or Steam)