TFC: The Fertile Crescent is a pixel-art RTS that resembles some of the classics like Age of Empires. It's currently in Early Access with Native Linux support and their new roadmap looks great.
Inspired by real history of the Near East Bronze Age era, TFC utilizes classic RTS elements while offering a unique perspective for the genre. One big change is how Food is not just used for building up your army but also changes how your population grows, and how quickly you can gain Knowledge Points to do research. It's a very interesting system that feels quite different to others like it.
Their new roadmap shows that across this year they plan to add in more single-player skirmish options, the ability to play against AI with friends online, an online co-op horde mode, neutral settlements, hotkey customization and unit stances. That's only for this year. Next year they have some other big updates planned too like new civilizations, new technologies, new map types like oceans and rivers, multiplayer matchmaking and more.
All sounding pretty great and it's easily worth playing right now.
You can buy it on Steam.