It's an all out, combination of endless tank battles and tower defense! Try to withstand aggressive, incoming enemy forces and you must protect your MCV at all costs. Build a variety types of tanks and towers to defend and attack enemies. Destroy the enemy MCV to accomplish the mission for each level. In survival mode, try to withstand waves of enemies as long as possible without losing your MCV.
Use 'A' & 'D' keys or <- -> keys or drag minimap to scroll the map. you can sell or repair your tower by clicking the sell or repair button on the bottom-right of the screen. 3 command buttons (on the bottom-left): Defend, Alert and Attack, respectively so you can easily command all units by clicking one of them. Press the SHIFT key to view all units' life bars. Hold the CTRL key and click on a friendly unit to make a force attack. Hold the CTRL key and click on ground to let your units move to that location to guard and attack enemies they face. More instructions and tutorials are available in the game.