Difficulty curve
How difficulty grows with the 3 phases, minutes, and overtime, with the live values from v0.9.0.
The formula
D = base × (1 + (phase−1)×0.5) × (1 + min×0.03) × (1 + overtime)
overtime = minutes_before_boss×0.6 + minutes_after×1.5 · the overtime clock changes pace when the boss dies
What speeds up, and by how much
| What | How much |
|---|---|
| Advancing a phase | +50% per phase: base 1.0 · 1.5 · 2.0 in phases 1–3 |
| Each normal minute (0–10) | +3% |
| Overtime before killing the boss | +60% per minute |
| Overtime after killing the boss | +150% per minute |
| Spawn rate in overtime | +50% per minute before the boss, +90% after (cap ×6) |
| Enemy speed in overtime | +7% per minute before, +18% after (cap ×1.9) |
| Finisher waves (after the boss) | every 60s: 4 + 1 per minute, up to 12, at ×1.8 speed |
| Co-op | +60% per extra living player (×2.8 with 4 players) |
| Horde composition | difficulty skews the spawn weights: each tier step (phase 2 and 3 enemies) multiplies its weight ×0.5 at difficulty 1 and up to ×1.25 at difficulty 4 or higher — the tough ones start out timid and end up dominating |
Watch outOvertime isn't symmetric: staying after killing the boss gets expensive two and a half times faster than staying before killing it.
Boss health
Bosses freeze difficulty the instant they appear: the mini-boss has 300 × D health (capped at 2,400) and the phase boss 6,000 × D, with no cap. The later you arrive, the fatter they come — but once on screen they no longer grow.
- The floor is kept: when you advance a phase, the difficulty reached is kept as a minimum — but the overtime ramp is discounted. In Expedition that floor travels with you from map to map, along with the clock.
- There's no phase 4 after phase 3: the game announces that you've completed the 3 phases and the run enters an endless overtime, where difficulty only stops rising once you die or abandon.
Verified against game v0.9.0.