Monsters will appear from the white whole after you select a weapon from the panel and put it on the map, going toward black whole.
There are three kinds of weapon: light machine gun, heavy machine gun and cannon. And a kind of roadblock. They are regarded as "towers".
You firstly should build some wall of roadblocks to limit monster's route. Arrange towers's layout to make good defense effect.
You can replace roadblocks with weapons, or upgrade a weapon to another kind.
Weapons shoot at monsters automatically in their valid range.
Click the blank area of the choice panel to cancel the building mode into normal mode.
click a monster will concentrate fire on it.
"Money" is used to buy weapons and roadbocks, and will be increased when a monster is killed.
"Life" will be decreased when a monster reach the destination.
You can remove any tower and get back harf amount of the price.