Tic Tac DS is a small game that I programmed for the Nintendo DS in C.
Currently it has 2 modes: Multiplayer and CPU Battle, The CPU has 3 difficulties.
To compile this program you need DevkitPro with DevkitArm and libnds. I recommend that you use the makefile that I have included.
Tic Tac DS is free and open source, it's distributed under the GNU General Public License.