F-52 was returning to the Earth safely after 12 years' successful mission. But..
[Introduction]
1. The concept of OE is based on the shooting game.
2. Each battle will automatically be progressed, however you can experience a huge difference of its efficiency growth by tapping or press firmly on the screen while the battle.
3. You can get battleships and weapons of your enemies while playing the game. It is also possible to upgrade or exchange with gained parts.
4. Have fun searching for hidden battleships and weapons. :)
5. There is no limitation in the challenge to improve yourself. Aim higher, try creating a cool battle ship combination of your own.
[Over Energy Version 1.05]