For a introductory C++ programming course at LIACS, I had to make a simple game of Ataxx. The game is in Dutch. First I made a console (CLI) version, and then I used the Ultimate++ framework to add a GUI.
The computer opponent is rather dull because my coding isn't that smart, but you might be interested in the UPP (Ultimate Plus Plus or U++) framework. Then it was still allowed to choose your own GUI libraries and I really liked it for a small app. In later years, the supervising professor (Walter Kosters, one of the best teachers I've had) decided to standardise on Qt.