I want to make a simple RTS game. But I have several problems. I hope someone can help me to solve them.

The first problem is that some terrain textures looks like a chessmate when I zoom out the camera.

I'm guessing that you didn't make your texture tile-able, and if you did, you did do so quite badly.

Pictures would always be helpful too.

The question also is: how far do you zoom the camera out? It could be that at quite some distance, you can see the repetition; but don't worry, when not too zoomed out, that won't draw a lot of attention!

So, I think I should fix the zoom range and scales of the world because on near distances it looks good.

It's a bit of playing around with texture scales and how far away you position your camera. It "most of the times" looks better when up close with a somewhat bigger scale.

Besides: People in general don't pay that much attention to the ground, but only see "overall" colourings. If you ever played WoW: did you ever look for repetition, or did you simply not care, or never even thought about it?

If you try to keep the detail from one part of your texture. Also a detail map would remove the chessboard effect. This effect just happens with certain textures with significant spots of detail (rocks, bumps etc). Some things like grass will also remove this effect.

Thanks for answers.