Complex sentence: Quantum Tic-Tac-Toe is our most thoroughly studied abstract quantum system, and while it has offered insights that have spawned new research, it also turned out to be a fun and engaging game, a game that provided good pedagogy in the classroom.
Split into simpler sentences: Quantum Tic-Tac-Toe became the most thoroughly studied abstract quantum system and offered insights that spawned new research. It also also turned out to be a fun and engaging game, a game which also provides good pedagogy in the classroom.