I personally love Naev and Mindustry
Right now I’m basically playing Beyond All Reason almost every evening. It’s a game in the Total Annihilation “tree” of games. A massive scale RTS. I previously played Supreme Commander and Planetary Annihilation, both of which are also inspired by Total Annihilation, but I have to say that BAR is really better than both of them. I almost can’t believe it’s an open source game. It’s still in alpha, but it’s been way more stable than most AAA games I’ve been playing recently.
You shold look into zero-k as well. I started out with BAR but found out zero-k more engaging
it’s about the single player storyline. It feels like BAR is more geared towards online/multiplayer, while zero-k has a proper full single player campaign. Don’t get me wrong, I played with BAR for quite some time and it’s still a great game, I just “clicked” better with zero-k.