TL;DR: It’s hard to say. I don’t think there’s a game which style I could name a 100% reference.
At first I had a vision of something along the lines of Stonehearth style, something that can be made by a non-artist (so-called programmers art):
Stonehearth is nice in its clear shapes, clean colors, nice ambient lighting. The plan was to have at least this far to get the NG going. As you can see – NG terrain has this style, although not as rectangular. Still Minecraft style houses are much too weird IMO, so the first NG houses were more vector-style like, with no textures in mind (Fisherman`s, Sawmill).
Through time I have collected many examples in my references folder, they all revolve around bright clean colors, cartoonish style, a bit schematic design. For recent example (yet unreachable) I find this Brewery absolutely gorgeous:
For the houses I’ve got some new experience with freelance artists and now that brewery style seems more tempting to try to achieve. It’s hard to find the right man for the job and price though, so I’ve got to get my hands dirty in texture painting and I kind of liked it. It comes out pretty nice and different from the Brewery example (cos that might be too contrast for a whole game to have). Let me finish the Sawmill and I’ll post it.
As for the level of graphics (that is purely technical side, art aside) – I’m going for 3D with a locked camera (you can only zoom in and zoom out). All modern 3D RTS games graphics are kind of similar. I guess 0A.D. kind of graphics is nice, clean, with some special effects, yet no overkill bloom, no blur.
Questions and suggestions are welcome 🙂