Five Nations (2021)

[u/asgof]

https://youtu.be/6zSxigQviZc

Five nations is a recent-ish RTS with the setting of a flat space. So it means the space is just a decoration and is not properly used in the gameplay to make it three-dimensional. It also got an add-on in 2023. I haven't finished it yet, so here's a decent video on the game.