Okay cool, understood. Thanks for the help, and i'll get this one fixed up and re-submitted!

In pixelart the challenge comes from using only the pencil tool at 100% opacity to create blends and effects. The second you use a brush or any other 'tool' you defeat the purpose of pixelart.
Understand that the origins of pixelart come from a time when hardware/software was incapable of doing these things.
The overall concept is 'one pixel at a time*'


*the bucket tool is the only tool exception to fill bigger areas where doing so OPAAT would just be silly and time consuming.

The lighting on the tree trunk clearly shows that you understand the OPAAT concept therefore in future work you should be fine.

Thanks. i actually didn't use any brushes, i used the pen tool using opacities. Is this not a good technique? Please help me out. Thanks guys

Its a friggin' masterpeice, but there are some gradients.

I hope you got a great score at school.
This fails at Pixeljoint because you have used CG gradients : (