The connection to the theme "frantic" is that the waves get faster as you go along, and there's a lot of micromanagement involved.

TIPS:

click a soldier, then a tree or iron mine to gather resources

the purple soldiers are ranged.  They will automatically shoot at enemies as long as they are standing still.

To order a soldier to go somewhere, shift-click the location

To use the trebuchet: click it, then click the place to shoot.