The Game Boy of Isaac - Team Kirby Devlog

We are "Team Kirby" from Telecom Paris, and for our end-of-year project, we set out to write a game, inspired by The Binding of Isaac, for the original Game Boy.

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29 June 2020

PAF Day 9: The Clock Is Ticking

by ChatPion

Only three days left, it’s now game jam time. It is possible to make a decent game in less than three days after all!

Floor generation

I worked on floor generation. First, I quickly wrote my algorithm in python, then I spent the rest of the day translating it into C. The error messages from SDCC were sometimes less than useful (I’m looking at you, “error line 221” when my file is 220 lines long…). Anyway, here are some generated floors:

(How to read: B = boss room, and numbers indicate the number of existing neighbours).

I intend on making a separate post about it when I have enough time.


AdameBF finally got his simple AI working. How intelligent is it? Well it can… die. But in a classy way!

Mixing C and assembly

After randomly poking around for a while, I stumbled upon how to modify global variables in inline assembly. Here’s some minimal code:

UINT8 var = 42;
static UINT8 static_var = 0;  // it works with static variables too

UINT8 main(void) {
    __asm__("ld hl,#_var");  // met la valeur de var dans static_var
    __asm__("ld a,(hl)");
    __asm__("ld hl,#_static_var");
    __asm__("ld (hl),a");
    printf("%d %d\n", var, static_var);  // prints 42 42
    return 0;

Note: static variables aren’t directly callable in the debugger (in Sameboy, print #_var would work, but print #_static_var) wouldn’t.

tags: mapgen - AI - assembly