You should really provide the reference so that people can see by themselves what you did and what you didn't.

(Cave Story) : https://cavestory.fandom.com/wiki/Bushlands?file=Power_Room.png

 

 

Personnally I think you did your best to redefine every single tile/pixel, but at this resolution it's always borderline, and even if you DO force yourself to change everything, there will be some cases where you know your version is worse than the original, so what's the point  :-/

A partial change is a fine exercize though, it's just not what the PJ gallery is for.

 

And in any case, never forget to credit the original explicitely! Cave Story is not as universally recognizable as, let's say, a Zelda III or GBA Pokemon screen (and even then, people don't usually recognize sceneries)

 

(edit : For what it's worth, and considering you had the extra challenge of making everything different including this tiny robot, I think you did very well. I see no weak spot, everything fits together, and if someone was given both your image and the original graphic to compare, they probably wouldn't be able to tell which one was made by the original artist and which one by the fan)