If smileBASIC is anything like Petit Computer, it's not that good at handling 3D or pseudo-3D. But if you really want to use SB, I suggest looking at raycast engines in other forms of BASIC and break them down so you can apply what you've learned into SB.

I wish my 3DS still woked (Well, it still works, but I broke it in half. long story short, I need a new body for it.) I'd be on this 24/7. I had the original Petit Computer, and it taught me a lot about programming. Nowadays, im using more powerful languages like Java instead of SmileBASIC. Moral of the story I guess is that learning a language like BASIC can teach you a lot about programming.