News via http://gbatemp.net/index_guest.php

Tic-Tac XO is a NES homebrew that puts a new spin on an old game. Players can swap spaces, use power-ups, and more. Please see the change log for more information.

QUOTE(Change Log)
• All new music, which you can hear in the downloadable NSF below
• A couple of instruction screens
• A very easy to locate easter egg that's not shown in the screenshots here
• Some minor cosmetic changes, seen in the screenshots below
• A computer that is unbeatable without obtaining power-ups
• A way to finish the game and get an ending screen

http://robertlbryant.com/gaming/ttxo.htm