You're the brass upright in the center. Tap and hold to spray — but the supply is weak (~7 psi static), so residual pressure drops as more heads open.

Put out fires to earn 🪙 Gold and level up. Leveling unlocks stronger sprinkler types (laser last, ~level 5). Tap 🔧 Build to add them to a slot — free, but each takes ~one wave to install (demolishing takes a wave too). Grab the end-of-wave upgrade cards (K-factor, supply, specials). Your Gold is always kept — every run banks what you earned plus performance bonuses. Spend it in the 🛒 Store on skins & head starts.

Green splitters break into two when doused; from wave 10, blue ELO flames shrug off small heads — only K11.2+ can put them out. Hold to wave 15 for the boss — then Act 2 brings grease fires (only foam works), ember swarms, backdraft, and hazards.