Warcraft II: Beyond the Dark Portal serves as an expansion pack for the original Warcraft II: Tides of Darkness, continuing the saga between the Human Alliance and the Orcish Horde. Players embark on a new adventure as the Alliance forces venture into the Orcs' home world of Draenor in an attempt to seal the rift that connects their worlds. The expansion introduces two new 12-map campaigns, one for each faction, along with 50 new maps and a fresh tile set that enhances the game's visual appeal.

The expansion also features five new hero characters for both sides, bringing unique abilities to the gameplay and enriching the single-player experience. However, it is noted that there are no new standard units, which may disappoint some players. Additionally, while the map editor remains unchanged, third-party programs can be utilized to incorporate new features, allowing for more creative gameplay options.