here Ive tried to arrange the palette by value to get a better look at it. Ive grouped some of the colors together. There are 4 groupings, Ill explain them each, from left to right
1. even though they are distinguishably different in hue they are pretty close in value. The palette might gain more versatillity by having a little bigger difference in value between them, but maybe not too much. This is just a thought though.
2. these look basically the same. seems like you were going for a warm and cool gray, but given the size of the palette its probably more efficient to just use 1 nuetral gray to give you room for 1 more color.
3. these 3 are all too similar. You can probably get rid of 1 entirely, and alter the value on another to be more of an intemediary value between the 11th and 12th colors (from the left). In your samply sprites youve already used the dark blue in lieu of dark green on the tree so maybe you dont need the dark green. You can use one of these colors to add in a lighter blue.
4. these just seem too similar.
the value step between the 2nd and 3rd colors might be too big, but maybe you dont need that intermediary value.
the sample sprites look pretty good though. Maybe try a full mock up or do color swaps with mockups made for arne's or dawnbringers palettes for tests.