Half-Life: Opposing Force review. Classic Game Room presents a CGR Undertow review of Half-Life: Opposing Force for PC developed by Gearbox Software and published by Sierra Entertainment. Opposing Force is a standalone "expansion" to the original Half-Life, and while it does change a few things up, it still feels very much like more Half-Life. That's a good thing, and it's a worthy addition to a Half-Life and/or FPS fan's collection. Or Steam library. This video review features video gameplay footage of Half-Life: Opposing Force for PC and audio commentary from Classic Game Room's Tristan.