Attempting to calculate the theoretical maximum score. I think the world is a cylinder, so I will use the formula circumference times height to calculate the surface area.
Circumference we can measure by following a circle and find out when we touch our tail. To not rely on eyeballing a circle we can use the land barriers that are pretty circular. It happens soon to the "end of the game" at ~35 apples. Height we can find by measuring when we touch our own tail by going perfectly centripetal. It happens at ~138 apples. The snake is built from circles, let's assume of radius 0.5/pi, the snake starts with 7 circles and gain a single 1 each time we eat an apple.
Thus, circumference is equal to 42, height to 145, area to 6090. Area of a single circle is 0.25/pi, thus the a maximum score is 2430pi or ~76529. As this measurement cannot measure more precise than 1 circle, the error bars are 42±1 and 145±1 for dimensions, therefore the area is ±187 and the score should be ±748pi which is ±2350.
Not that close I'd say. I've managed to get to here (also grey rock is more appetite efficient as it takes only 640 appetite per white gem as compared to 900 from a metal)
There was 1 gem from eating all bring and grass, and two more from spending the appetite. To merge two greens we therefore need one more blue gem, and that is a lot; it just appears to look much less due to all of these compressions
I've managed this score, lower I think due to inefficent gem placement next to this east wall. So I'd think the 5088 is indeed the maximum, maybe can be pushed up to 5090 but not much higher. The main source that can be optimized is this upper-left puzzlebox
I have managed to extract everything from it save for these three grass tiles. Nothing is theoretically stopping it from having a better solution. I have then merged the 1-gem in the corner with a leftover from somewhere else
