For terrain, use the triangle plugin. It’s literally what the devs used to make most of the maps. Using separate blocks as the terrain is extremely difficult to piece together accurately. Also, please use more saturated colours when colouring in the terrain. The colour you used for the sand is extremely cliche/overused.
You don’t have to saturate the colours, but it looks a little nicer. Adding a SurfaceGui and dimming a frame to change the colour is a great way to richen the colour. Observe the following image, comparing two parts; one without and one with the SurfaceGui:
I used the same colour and texture on both bricks but added a SurfaceGui and so I could add a frame with 0.7 transparency and change it to whatever colour. However, the same process would have to be used for every other terrain block, which could get tiring, but it looks that much better. You might have to change which side you put the frame on, though. This is a property of SurfaceGui. I used the “Top” side for this example.
Other than that, looking forward to what the map will become. Great build so far. ^-^