Hmm, well first off try to add a yellow fog or something bright to give it more effect.
Next try to find a brighter sky or make the mountians near the sun next time/ the darkness doesnt really fit. Try n mess around with the lighting also , dusk,midnight,daytime,
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Picture one - a lil end of world on first picture on right side, flowers growing on dirt near the middle (idk) and it looks like those small copperish-gray trees dont fit in try to smooth up the waterfall near top and in the middle. Blue rocks? bottom right corner no doodads or tile variation
Picutre two - Not sure, but i dont think grass grows underwater near waterfalls, there is a big mass of doodads near the waterfall - not alot in other places, right side has a lot of dirt, try and mess around with the bubbles they can sometimes look like a waterfall splash going down.
Picture three - change the color of some of the doodads to match the grass, looks like theres about 30 doodad varaitions, idk it looks a lil messy, that log is ugly, I dont know if you did this but try to smooth some of the terrian near the waterfalls edges.
+ whats with the change of water color?
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I hope this helps ( im not that good of a terrianer either)