It is variously known as Simple 2000 Series Vol. 103: The Chikyuu Boueigun Tactics in Japan and both Earth Defence Force Tactics and Global Defense Force Tactics in Europe.
Players assume the role of a GDF Commander and control GDF units in turn-based missions against the Invaders. Missions take place on 2D hex-maps, with attacks depicted by brief animated cutscenes, which may be toggled on and off in the options menu.
The game has 50 stages for the campaign of GDF + 50 stages for the campaign of Invaders. Through the stages the level of units increases, they get a new weapons, which in the game are 393 different types.
|Main series and remakes||Monster Attack • Global Defence Force / Earth Defense Force 2: Invaders From Planet Space • Earth Defense Force 2017 / Earth Defense Force 2017 Portable • Earth Defense Force 2025 / Earth Defense Force 4.1: The Shadow of New Despair • Earth Defense Force 5|
|Spin-offs||Space War Attack • Global Defense Force Tactics • Earth Defense Force: Insect Armageddon • TapWars: Earth Defense Force 4.1 • Earth Defense Force 4.1: Wing Diver The Shooter • Earth Defense Force: Iron Rain|