Some versions of the game reward you for holding onto gold. Check if your specific version grants interest; if so, never spend your last 100 gold unless it is a life-or-death situation.
Aerial waves are the "run killers." Keep enough gold in reserve to quickly place SAM (Surface-to-Air Missile) sites only when the flyers appear, then sell them immediately after to reinvest in ground defense. xeno tactic cheat high quality
It is better to have one Level 3 tower than three Level 1 towers. Higher-level towers usually have better range-to-cost efficiency. Weapon Synergy and Exploits Some versions of the game reward you for holding onto gold