I like the minimalistic low poly design and your choice of palette. This is a very creative take on the theme that I haven't seen yet and don't think I'll be seeing again.
Once I understood the best moment to place a server, I didn't really have any more choices to make in the game. Offering varying kinds of serveers/upgrades, recognizing grid patterns and adjacency, replacing old units whose efficiency weakens, or adapting to differences at certain times of day, there's many ways you could develop this foundation to add more options for the player to explore over time.
Nice work nonetheless. Would be interested to play again if you develop it further.