Not PlanetS, Though That One Is Free Too
Planet S just got out of early access and is, at least for the time being, free to pick up. The game looks similar to something early in the Anno series, with the biggest difference being that it takes place in space. Instead of building an empire on Earth, you pick one of 14 procedurally generated planets to start your colonization. The planets will have a variety of resources and terrain, each relatively unique, so chose carefully. This being a strategy RTS, the initial colony is only the first of many for once you have a solid base you need to start colonizing the other planets before others do.
The game can be played with up to four players online, or you can try out the AI. Rock, Paper, SHOTGUN found the AI options a little limited and had more fun playing with real people, but you can certainly use them to learn how to play. The research trees should be somewhat familiar, with higher tiers unlocking new buildings and other tools to bring you to victory. You can win by the sword or peacefully, as diplomacy is an option.
For what it costs, you should get your value out of Planet S.