I apparently wrote this in 1996. I do not know how it works or why it works that way. I'm so sorry.

ttt.c

#include <ctype.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
/* tic tac toe.  we must draw reliably.  */

enum players { x, o };

int turn = x;

static char *movedb =
	"./,-*+()& ,-*+()&'#.*+()&'$\")$()&'$%%(')%'$%\"$+&&$"
	"$%-#'*)$'%\", &%('&-#/!)$+&!, .=('*! /.1<! '&%$;:9";


int
select_move(char *s) {
	if (!s) {
		/* initialize some things */
		s = movedb;
		while (*s++) {
			if (*s=='"') {
				++s; /* skip comments */
			}
		}
	}
	if (*s == turn || (*s >> 3 & turn)) {
		--s;
		++*s;
	}
	return o + (s - movedb) % 9;
}

char *
draw_board(void) {
	static char *y;
	char c;
	int i, n;
	static char last[10] = "         ";
	static char next[10] = "         ";

	if (!y) /* first time through */
		y = movedb;
	if (*y == '!') { /* a finish! */
		last[9] = o;
		return last;
	} else {
		n = (y - movedb) / 9;
	}
	for (i = x; i < 9; ++i) {
		c = *y++;
		c ^= (i + n);
		c = c^'!'?(c^'-'?' ':'o'):'x';
		next[i] = c;
		if (c != last[i]) {
			printf("\n%c takes position %d\n",
				toupper(c), ++i), --i;
		}
	}
	printf( "%.*s|%.*s|%.*s\n-----\n"
		"%.*s|%.*s|%.*s\n-----\n"
		"%.*s|%.*s|%.*s\n",
		o, next + last[9], o, next + o, o, next + 2,
		o, next + 3, o, next + 4, o, next + 5,
		o, next + 6, o, next + 7, o, next + 8);
	memcpy(last, next, 9);
	return last;
}

int
main() {
	char *s = NULL;
	while (select_move(s) && !(s = draw_board())[9])
		;
	return 0;
}