I've heard of Mount & Blade and Civ 4, but I don't know the exact limits. I haven't tried python for myself but I've heard it's good enough for most game development stuff, unless you want to compete with the absolute cutting edge games. You can probably make a MTW1 or Shogun like game in Python with reasonable framerate on modern computers. As for an RTW engine I can't say with certainty whether it'll work or not, but it'll probably work if you choose to switch to sprites at a quite short distance... Then again, the rendering of the actual landscape will also take a lot of triangles so I can't really say how well it'll work, especially if you want things like advanced sky, shadows etc....
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