Yes, I know that there are tons of ASM snake games on ticalc.org.  Yes, I know that they are usually frowned upon. 

One of my friends wanted me to make a snake game for the calculator.  I accepted her "challenge" and am now obligated to make an original snake game.  I am already doing crystal timed grayscale (like the one for Thepenguin77's chess game) if compatible and using a different type of timing for the other calcs.  I have also been thinking of some type of level editor, but I'm not really sure what else I can add.

If you have any ideas, please post them.

2 player

Add special effects and powerups: extra speed, slow-down-time, Invincible, magnet, go through walls(wraps around screen), Extra Life, Extra Fruit... etc, etc, etc.

the snake game that comes with GNewsense (linux distro) is exactly like that.

Have multiple snakes that can kill each other.

There was an ios game I got that did that. Here's a video:

Make the graphics awesome

Run the game at 20 fps and have a 1 byte memory location called clearance and another called clearanceCounter. Initlialize clearance to 0 and clearanceCounter to 3. At every interrupt, decrease clearanceCounter: if it is nonZero, store it and continue, if it is zero, reset it to 3 and set clearance to 1. In your main code loop, have a routine called waitForClearance. Call this every frame. The code of it should look like this:
waitForClearance:
ld a, (clearance)
or a
jr z, waitForClearance
xor a
ld (clearance), a
ret

What this does is it perfectly syncs your graphics and your grayscale. Every frame is shown for exactly 3 screen updates. This will ensure that the grayscale looks the best it possibly can for moving objects. An added plus is that this system will allow the game to slow down if it starts to lag and get right back to where it was when it stops lagging.

You could also make the frame rate 10, 5, 4, or 2. But... really only 10 and 20 are reasonable.

I have some ideas...

1. Have a plot.
2. make it some other creature than a snake, like a caterpillar or an eel.

You should trip people out by having a stobe light effect, or at least a random color invert

I'd be careful about that, strobe lights are known to trigger seizures (and migraines in holmes).