First expansion for War for the Overworld available Friday

The add-on is free to early purchasers

The first expansion for the video game War for the Overworld, called Heart of Gold, will be launched Friday. The game is available on Steam for Windows, Macintosh and Linux.

The expansion continues where the original game left off, with four new campaign levels, a smattering of new defenses, units and spells,and a new dungeon theme.

Anyone who purchased War for the Overworld on or before May 2, including those who participated in the game's Kickstarter, will be able to download Heart of Gold for free when it launches.