What changed from the first game
The original Slay the Spire was a fixed climb: Act 1, then Act 2, then Act 3. The sequel branches. When you enter an act that has a variant, you are randomly offered one of its two paths, and those paths differ in environment, enemies, events, and bosses.
The act map in the current build
Mapped from the 115-enemy dataset by where each enemy actually appears:
| Act | Variant | Encounter rows in dataset |
|---|---|---|
| Act 1 | Overgrowth | 44 |
| Act 1 | Underdocks | 25 |
| Act 2 | Hive (single) | 32 |
| Act 3 | Glory (single) | 24 |
Ten enemies in the dataset have no act assignment (mostly boss or special encounters), which is why the rows do not sum to 115.
The split is visible immediately: Act 1 is the only act with two variants right now — Overgrowth (nature-themed: fungi and beasts) and the Underdocks (aquatic sewers: mutants and vagrants). Acts 2 and 3 are single variants — the Hive and Glory — at early access.
What this means for routing
Branching multiplies content. The same Act 1 can play completely differently depending on which variant you draw, and because the enemy mix changes, your Affliction exposure changes with it (see Afflictions). Act 3 routing matters most: taking the alternate Act 3 bosses skips Doormaker’s Afflictions entirely.
What is still coming
Mega Crit has confirmed Acts 2b and 3b for post-launch early-access updates. Until then, Acts 2 and 3 are the Hive and Glory as listed above.
Where to go next
Monsters database lists every enemy and the act it appears in. Afflictions covers the mechanic that makes act routing a defensive decision.