As part of ECE 92 (Projects in Electrical and Computer Engineering), I designed and built a robotic arm that plays a pencil-and-paper tic-tac-toe game with either 1 or 2 players. The system consists of an ARM based Arduino MCU board, a light weight 3 servo robot arm modified to hold a pen that floats vertically to handle variations on the board and arm angles, an LCD that displays the score, and two keypads for user input. The C++-based embedded software calibrates the arm servos which then draws the 9-square game grid, scans the keypads, updates the display, and draws the X and O game symbols based on the user input or its internal game algorithm.
The display poster is available here and the related source code can be found on GitHub.