Complex sentence: This was the first ever game forfeited in AFL history, which occurred due to the Gladiators (representing the AFL player's union) going on strike to protest on-field safety concerns and contract disputes with AFL management.
Split into simpler sentences: This was the first ever game forfeited in AFL history. The forfeit occurred due to the Gladiators (representing the AFL player's union) going on strike to protest on-field safety concerns and contract disputes with AFL management.