What is the picture on the title screen?

Nice I didn't see the download link earlier. I'll try the game on my calc when I get some time.

I've tuned the settings (speed, gravity, ranks, the speed at which the size of the gap decreases, and now it's much easier to go up, so no need to furiously hammer the up key anymore), changed the way the cave is generated and modified some minor things. Now the cave has things like these (just slopes I guess):

Also now the game doesn't lose the high score as soon as you close the document. Now when you do quit the game, it should ask you whether or not you want to save the document, pressing yes will save the high score. The new download link should be there now.

Do you use a var.store to 'externally' save the score to a math variable ?

Yes, but I tried accessing it externally without success (which is a good thing). Maybe it creates its own namespace only accessible through the document itself.

Also now the game doesn't lose the high score as soon as you close the document. Now when you do quit the game, it should ask you whether or not you want to save the document, pressing yes will save the high score. The new download link should be there now.

That's a neat way to do that.   It sounds cool.

Great !
This game looks very nice, congrats !
(But the picture on the title screen must be quite heavy and not really useful)

Well, the picture on the title screen is the title screen picture after all. It might be heavy as raw text, but once it is processed and compressed by TI's tool, it gets very light. The "not really useful" is more subjective than anything else, some people might prefer to have a text-based game without graphics at all. They could just give out all those commercial games you see in shops in a small cardboard box; the artwork doesn't add anything to the game. I personally like to have a title screen, I guess I must be a perfectionist.

Okay new update. First of all I changed that depressive title screen into a less depressive one (long live monochrome displays! ), and now the high score shows up there also. Then I added the "floating walls" to spice up the game, just cruising straight forward in the cave won't be enough anymore. I fine-tuned the settings and cleaned up the chamber of horrors (i.e. source code) into a polished piece of art. Also some slight performance improvements were made. Download link's there now.

Yes it does look good, but it's only decorative.
Of course I prefer games with wonderful graphics rather than text-only games.
The picture is heavier than the code, and I think that's strange... But this is not a big problem.

Well the whole point of graphics is that it's just eye candy. A well-decorated and good-looking dish is always better than the same food in a rusty old barrel.

This looks nice! Also I like how you use different text fonts for the numbers at the bottom.

Also since the title screen is 16 level grayscale in the first screenshot, how large is it on calc? Somehow I think it must be larger than the entire game, but I could be wrong

Well once the game has been saved, it takes about 16K of space, which is practically nothing. The ZIP compression their format uses does a good job in compressing the picture (and anything for that matter), so no worries there.