Sea units were reintroduced which were absent in Reign of Chaos. The expansion adds new units, buildings and heroes for each faction, two new auxiliary races, five neutral heroes (with three more later added by patches) as well as a number of tweaks to the gameplay and balancing. Additionally, the expansion contains Act I of a separate Orc campaign that is independent from the main storyline with Blizzard releasing Acts II and III via patch in December 2003, taking in player feedback of Act I when developing these chapters. The single-player unfolds from the perspective of two new protagonists-the Night Elf warden Maiev Shadowsong and the Blood Elf prince Kael'Thas-as well as returning protagonist Arthas Menethil. The Frozen Throne builds upon the story of Reign of Chaos and depicts the events after the main game's conclusion. It was released worldwide on Jfor Microsoft Windows and Mac OS X. Warcraft III: The Frozen Throne is the expansion pack for Warcraft III: Reign of Chaos, a real-time strategy video game by Blizzard Entertainment.