Exclusive modes

An exclusive menu/test mode should own the whole cycle:

exclusive-mode.gpc

int menu_open;

main {
    if(menu_open) {
        block_all_inputs();
        menu_tick();
    } else {
        gameplay_tick();
    }
}

function menu_tick() {
    // menu-only state and output
}

function gameplay_tick() {
    // normal logic
}

Suppressing a few menu buttons is not equivalent to skipping gameplay logic. A later gameplay block can still mutate state or overwrite outputs.