Screenshots are not really saying much. (making a nice scene just shows if you know how to set up a nice scene, or in other Terms: a detailed AK-47 model does not make a good Shooter already) I judge when I see a demo or at least a througout gameplay video.
The point still stands: first make a smaller project to get familiar with the engine and workflow.
... I actually plan on making an RTS again, just not shure if I should use gamestudio again or Java+OpenGl, It would be more work, but the advantage is it can run on all systems and even directly in a Browser.
And I could keep the whole game (without the libraries) under 100Kb.