This is a multiplayer only Half Life mod. You play as humans or zombies, The goal is to wipe out the other team. You have an arsenal of items at your disposal witch can help you do this.
This map pack was released after the mod. Bigman10 made all the maps. Original Description from Planet Half Life (fixed for spelling): 5 New maps for OutBreak 1.1 ob_downtown = a big city map. ob_hellsville = a school ob_highrise = the top 4 floors and the roof of a sky scraper ob_not_safe = a bunket in a forest ob_the_deep = a big bunker/research facility