Survive forever! Enemies keep coming with increasing difficulty.
Every 5 waves: speed +5%, HP +10%. Every 10 waves: new enemy type. Every 20 waves: path changes!
Waves 1-10: Basic+Fast | 11-20: Tank+Flying | 21-30: Healer+Shielded | 31-40: Splitter+Stealth | 41-50: Boss | 51+: ALL
Towers upgrade INFINITELY (costs double each tier). +20% dmg, +10% range, visual growth.
+1 life every 10 waves. Auto-send toggle available. High score saved!