Past Day 30, passive harpooning becomes mathematically insufficient. You must transition from a stationary scavenger into an active naval explorer. This phase is characterised by the introduction of the metallurgical processing loop — and it is the most common progress wall for new players.
Locomotion first
Build the Sail or Paddle before you do anything else. With only drift propulsion, you cannot intercept procedural islands, and without islands you cannot reach the Iron Vein nodes that drive this entire phase.
The Smelter is the gate
Construct the Smelter as soon as you have 15 Iron Ingots and 10 Bricks banked. Without the Smelter, raw Iron Ore is functionally worthless — it cannot be processed into the Iron Ingots required for Bonfire Level 4.
Bonfire Level 3 — Chemistry Station and Engine
Upgrading the Bonfire to Level 3 unlocks the Chemistry Station and the internal combustion Engine. Both are mandatory for the late-game weapon and consumable economy. Don't skip them.
Bonfire Level 4 — the alloy shift
Level 4 requires a composite injection of Iron Ingots and Bricks. This is the visual and mechanical shift from highly flammable wood to reinforced alloys. Your base material transitions here. Survive the metallurgical bottleneck and the Industrial Phase opens up.
Common failure modes
Players who skip the Smelter end up with mountains of raw Iron Ore that they cannot use. Players who skip the Engine end up at the mercy of the procedural wind vector. Players who skip the Bonfire Level 4 composite get wiped by mid-game fire hazards.