The Earth War MOD is a free add-on for the award winning game Half-Life. The story behind it is too long to go into here, but there are links to it from here.

The MOD is both single and multiplayer, with the multiplayer portion being released first.

The single player part will be the story of the war on Earth, played out by the key player, Nathan Bright. There will be new monsters, allies and maps; and you will have a variety of weapons and abilities under your control. Among these abilities are those of flight, concealment and shielding. However, you must earn these abilities with experience gained from killing monsters, or solving puzzles.

The multi player portion will have several modes of play. The first one to be released will be the round-based teamplay game. Each team must kill the other in order to win. You earn experience for killing your opponents, through which you can become an awakened human and have access to psychic abilities; but they get money in compensation. To put it in one way, if you've just become an awakened human who can fly and has the most powerful shield available, someone on the other team probably has enough money to buy a homing low-yield tactical nuke.

The next mode of play to be released will be the cooperative team play. During the game you must complete several objectives, be they find out some information, bust out someone from an enemy encapment, kill all the enemies, or assasinate just one... it all depends on the mission. Each mission may also twist away from what you originally thought... a simple ambush could turn into a mission where the entire future of the human race is at stake.