An unusual, global, high-intensity "red tide" (actually a large-scale activation of spores triggered by unknown cosmic rays or specific environmental factors) broke out in a specific sea area. The activated spores ("red dust") are dispersed by monsoon winds and ocean currents, forming a "spore rain/dust storm" covering large areas of land. Animals and plants that come into contact with activated spores begin to undergo unpredictable, rapid, and violent mutations (such as plants growing wildly and becoming aggressive, animals going berserk, and small biological fusion distortions). What's even more deadly is that humans who inhale or have skin contact with high concentrations of activated spores will experience a transformation similar to "zombification" (but set to "parasitic neurosis" or "extremely aggressive fungal infection" that is more in line with biological logic), lose their minds, become highly aggressive, and spread extremely quickly.
Very well written, immersive experience