Well, dont bother saying this is a copy of defend your castle... there is only one thing similar which is u are defending your castle, but with more enemys, spells, different system, AND MUCH MORE!
The Zeta forces are trying to take over our secondary base, we need you to slow down their progress. The more you kill, the more cash you'll get. Get ready, they're coming and shoot as many of them as possible and reach the Zantor Station at the end of the level to proceed further.