Description from GOG.com:
Join the Brotherhood of Steel, a technological revival group dedicated to restoring the world to its former prosperity through science and whatever means necessary. Take part in a quest to reawaken long-dormant technology in order to defeat a powerful enemy in the one of a kind Fallout Universe. Each mission involves various hostile obstacles that must be overcome using tactical skirmish warfare. The player controls up to six detailed characters in the single player mission-based campaign or they may use their chosen squad online in multiplayer battles. Squad-members improve with experience, increasing their skills and earning perks. Many varieties of weapons, from handguns to rocket launchers, allow the player to lay waste to his enemies. In addition, the fighting isn't limited to pedestrians, as squad-members may take the action to the streets with armed vehicles. As a Brotherhood of Steel initiate you will challenge hordes of ghouls, mutants and other radioactive nightmares. Always outgunned and outnumbered you will fight in hopes of restoring humanity. You're in the army now... so, welcome to the Wasteland! You are the wretched refuse. You may be born from dirt, but we will forge you into steel. You will learn to bend, if not you will break. In these dark times, the Brotherhood - your Brotherhood â€“ is all that stands between the rekindled flame of civilization and the howling, radiated Wasteland. Your weapons will become more than your tools, they will become your friends. You will use your skills to inspire the lowly and protect the weak... whether they like it or not. Your squadmates will be more dear to you than your kin and for those who survive there will be honor, respect and the spoils of war.