The Red Alert of Sci Fi classic RTSes!
If Red Alert was the alternate history all hailed RTS that used WWII as a backdrop
to create the game, Total Annihilation: Kingdoms is the all hailed and critically acclaimed same era Sci Fi inspired strategy. I wouldn't say it bears the mark of StarCraft
because it is more prone to the same gameplay mechanics as Red Alert, which is, a lot more emphasis on base building and other managerial tasks and, generally, tactics that put more units and massive offensive front and center, rather than the highly mechanical, number of clicks and button presses accountable for micromanagement that StarCraft asked of you. Don't know if this last phrase makes sense, so I'm going to say it in other words to make sure you understand: In Total Annihilation: Kingdoms you are better of with more units going for a blunt attack, instead of you needing to be great at micromanagement, as StarCraft required. Eh, there, I understood what I wanted to say, maybe you did too, mission accomplished! Hehe! Graphically, Total Annihilation: Kingdoms is a top down, well polished, black fog of war wielding, almost 90 degrees topdown view game, with relatively minimal interface and interface management and, overall, very easy to learn. A classy, snazzy, razzle dazzy RTS which I love, and if that is a measure to go by, I'm sure you will appreciate it too! Else see the other games I linked to, especially Red Alert, my all time favorite (LAN multiplyer) RTS of choice.