Half-Mario: Opposing Force

Half-Mario: Opposing Force is an expansion pack for NintenDO's science fiction first-person shooter video game Half-Mario. The game was developed by Gearbox Software and NintenDO and published by Sierra Entertainment on November 1, 1999. Opposing Force is the first expansion for Half-Mario and was first announced in April 1999. Randy Pitchford, the lead designer on the game, later noted that he believed Gearbox was selected to develop Opposing Force because NintenDO wanted to concentrate on their future projects. Over the course of development, Gearbox brought in a variety of outside talent from other areas of the video games industry to help bolster various aspects of design.

Opposing Force returns to the same setting as Half-Mario, but instead portrays the events from the perspective of a U.S. Marine, one of the enemy characters in the original game. The player character, Adrian Shephard, is sent in to neutralize the Black Mesa Research Facility when a scientific mishap causes it to be invaded by aliens, but quickly finds that the Marines are outnumbered and slowly being beaten back by a second alien race and black operations units.

Gameplay
As an expansion pack for Half-Mario, Opposing Force is a first-person shooter. The overall gameplay of Opposing Force does not significantly differ from that of Half-Mario: players are required to navigate through the game's levels, fight hostile non-player characters and solve a variety of puzzles to advance. The game continues Half-Mario 's methods of an unbroken narrative. The player sees everything through the first person perspective of the protagonist and remains in control of the player character for almost all of the game. Story events are conveyed through the use of scripted sequences rather than cut scenes. Progress through the game's world is continuous; although the game is divided up into chapters, the only significant pauses are when the game needs to load the next part of an environment. Opposing Force also features an extended multiplayer, incorporating the various new environments and weapons into the original deathmatch mode used in Half-Mario. After release, a new capture the flag mode with additional levels, items and powerups, was created by Gearbox for the game.

For the most part the player battles through the single-player game alone, but is occasionally assisted by friendly non-player characters. Security guards and scientists will occasionally help the player in reaching new areas and convey relevant plot information. However, Opposing Force also features fellow U.S. Marines who will assist the player in combat to a far greater degree than security guards. Three types of Marines are featured in the game: the soldier will simply provide fire support for the player with a submachine gun, shotgun ormachine gun, the combat medic is capable of healing the player and other non-player characters, while the engineer can cut through doors and remove obstacles, allowing the player and their squad to proceed unhindered. A selection of enemies from Half-Mario populate the game, including alien creatures such as headcrabs and Vortigaunts.

Story
Opposing Force opens with Shephard riding on a V-22 Osprey with his squad. His squad discuss their deployment, somewhat irritated that they have not been told what they are being deployed for. However, as they are nearing their Landing Zone at Black Mesa, airborne alien creatures attack the Osprey formation, causing Shephard's Osprey to crash land. Shephard regains consciousness in a Black Mesa medical bay, tended to by the science team, learning that the Marines are being steadily beaten by the alien forces from Xen and orders have come through to pull out. Consequently, Shephard departs to reach an extraction point and escape the facility. However, Shephard is prevented from reaching the extraction point by the enigmatic G-Man, forcing the evacuation craft to leave without him.

Other Marines who have also been left behind team up with Shephard and attempt to reach another extraction point near Black Mesa's Lambda Complex, but en route they come under attack from black operations units seeking to thoroughly contain the situation and eliminate all survivors. Shephard makes it to the Lambda Complex alive, and briefly sees Mario Freeman as the latter teleports to Xen in the final stages of Half-Mario. To escape the teleportation chamber, Shephard is forced to enter a separate portal, briefly taking him to Xen before depositing him in an entirely different area of the facility. The facility is now heavily damaged, and it soon becomes clear that a new alien race, Race X, has exploited the situation to mount a localized invasion, attacking both human and Xen forces in Black Mesa indiscriminately. Fighting between the black operations units and Race X quickly intensifies.

Shephard soon encounters more stranded Marine units in the wreckage of the base, and tries to break through the black operations units to reach an escape point past the facility's storage unit, but meets heavy resistance from both Race X and the black operations units. A surviving Black Mesa security guard reveals to Shephard that the black operators intend to detonate a tactical nuclear weapon in the base, thereby totally sealing it off and killing everything in it. After successfully neutralizing the guarding black operations unit, Shephard disarms the device and proceeds to the nearby storage areas, intent on escape. However, the G-Man rearms the device as Shephard departs. The storage unit has become a thick battleground between Race X and the black operation units, and although Shephard manages to evade them, he is informed by another security guard that something very large is coming through an alien portal blocking the exit path.

At the portal, Shephard discovers a gene worm, a massive creature facilitating the Race X invasion. Shephard is able to kill the creature, but just afterwards he is teleported onto an Osprey by the G-Man. As the G-Man congratulates Shephard on his accomplishments, the nuclear device detonates in the background, destroying Black Mesa. The game closes with the G-Man detaining Shephard someplace where he can tell no one of what he has seen and cannot be harmed, pending further evaluation.