: You don't click an "upgrade" button. To make a tower stronger, you must physically add more components or redesign it. Essential Strategy Guide
: Almost everything (99%) is physically simulated. Bullets can bounce off surfaces, and obstacles can physically block rushing enemies. The.White.Laboratory-PLAZA.rar
: Use propeller probes for scouting and defending against airborne threats that ground towers might miss. : You don't click an "upgrade" button