L# is your height variable. Change the second and first Y values, respectively, in your GFILLs to be decreased by L#. If it seems to be inverted when testing, change them to increase by L# instead.
E.g.: Change the 199 in the first one like this...
GFILL 0,0,399,119-L#,RGB()
And the 120 in the second one like this...
GFILL 0,120-L#,399,239,RGB()
Do you have a height variable for the raycaster? You could use that to change the GFILLs so that they move with the walls' bottom instead of a constant half-screen drawing.
In this case BUTTON(2) AND #A will work only if the A button was pressed (but not if it was being held).
You can also do BUTTON(2) AND (#A OR #B OR #X) to detect if either the A, B or X button were pressed. You can place as many buttons as you want that way.
Feel free to ask if you need more help or clarification!
You can write a button conditional like this...
IF BUTTON(0) AND #A THEN 'ETC
You can replace the #A with other constants.
The number in the BUTTON instruction represents what kind of button input you want to get. 0 (or none) gets input of a button getting pressed and held. 2 will get you input of buttons only on the time they get pressed (not held). Look up BUTTON's help entry for the rest.
The button command should be used with a logic gate accompanied by button constants. You can find all button constants in BUTTON's help entry, but they are pretty simple to remember. They are...
#A, #B, #X, #Y, #L, #R, #UP, #DOWN, #LEFT, #RIGHT.
If you have a New 3DS you can also use #ZL and #ZR.
After this, you can use a simple conditional to determine if a button is being pressed.
No tengo mucho conocimiento en el área de encriptación, aunque veo que has desarrollado un algoritmo sencillo y fácil de usar. Aunque similarmente al cifrado César, es un tanto simple, asi que el código podría ser roto fácilmente a través de fuerza bruta.
De igual manera, parece una buena forma de cifrar mensajes sencillos.
Técnicamente existe el Tab en SmileBASIC, pero no lo puedes escribir con el teclado por defecto. Podrías reemplazarlo con el CHR$(58025) o el CHR$(58016), los cuales también son invisibles y tecleables. (Son los caracteres en la esquina inferior izquierda en la sección con la pica.)
You probably should call it something else, though. The name Yahtzee is copyrighted. However, you can use Yatzy or Yacht, which belong to public domain.
Erase lines 17 and 18. You only need to have one ELSE. (You can have as many ELSEIFs as you want, though.)
Also, when coding on the console you should limit yourself to changing variables and printing text on the console. Modifying graphics and using GOTOs may end up in unwanted program behavior. To get around it you can set up hook variables to run anything else outside the console.
You weren't meant to copy that. It was just a representation of your main game loop, if you had it.
You need to develop this logic on your own. You won't always get to copy. If you don't understand this kind of logic yet, I'd suggest looking for a programming course online. Even if they use other programming languages, the main logic still applies. I'd suggest the course provided by Khan Academy.