I'd tone down the internal lines on those units.
I can't make out the first one actually... but I think I see a cockpit. It's always a pity when you're especially proud of something and people don't get it. Sometimes blindness can strike you as you work. You know exactly what you're doing, and you're so familiar with ever knob and edge that you forget to back out and get a fresh view of things. After a few hours (or a week) away from the piece you usually get a more objective view though.
On the mountains, I'd remove any lines separating the base from the ground, or make them very vague. All edges doesn't have to be subtractive lines! You can also use a lighter line to suggest a concave curvature reflecting light (curvatures are more likely to have a highlight).
I think the colors used on the mountains feel a bit sick. I'd use the same colors for both the ground and mountains (or hills). A purple gray for shadow, then a warmer sienna brown.
The jaggies on the isle coast cliffs feels a bit too gritty.
You might not want to detail the ground with random noise if the game uses simple grid mechanics. If you do have a texture, maybe it should be generic and show the tiling edges or some repeating artifacts since that's useful information to the player. Check out how Bitmap Brothers'
Z did ground though. I seem to recall they used 2 temperatures for the dents/pebbles and regular flat ground. Something to ponder maybe.
