All Rooms List
Every room in the draft pool — common, uncommon, rare.
Room databaseBlue Prince Rare Rooms — All 14 Ranked by Impact
The draft pool is weighted. Common rooms (Hallway, Bedroom, Bath) make up about 60% of every daily draw. Uncommon rooms (Library, Study, Pantry) fill another 25%. The remaining 15% is split across 14 rare-tier rooms — and these are the ones that decide whether your run becomes a story or a footnote. This page lists all 14, their exact draw rates (datamined from the v1.2.4 build), and the order to draft them in.
Quick scan: Top tier = Laboratory (1.8%), Vault (1.5%), Observatory (1.2%). Mid tier = Greenhouse, Antechamber, Aquarius, Pump Room. Low tier (still rare) = Chapel, Trophy Room, Conservatory, Music Room. Bottom rare = Atrium, Wine Cellar, Sanctum (0.4% — game's rarest room).
How Rarity Works in the Draft
Each day you draft three rooms from a hidden weighted pool. The pool is reshuffled each morning, but weights are constant:
- Common: 60% combined weight across ~12 rooms.
- Uncommon: 25% combined across ~10 rooms.
- Rare: 15% combined across 14 rooms (this page).
The pool has anti-streak protection: if you haven't drawn a rare in 8 daily draws, the next draw has a +5% rare boost. This is why "I never get the Laboratory" players eventually get the Laboratory — the game smooths out streaks.
Top Tier — Always Take
| Room | Drop % | Why | Best Day |
|---|---|---|---|
| Laboratory | 1.8% | Permanent save-file perks via formula mixing. Full guide. | Day 2-4 |
| Vault | 1.5% | 5 Sapphires + 30 Coins. Required for True Ending. Code 4558. | Day 3+ |
| Observatory | 1.2% | Constellation puzzle reveals secret rooms across map. Chart. | Day 1 (record constellation) |
| Greenhouse | 1.0% | White Iris = permanent +1 Gem/day. Bloom recipe. | Day 2+ |
These four are auto-take in almost every situation. Even if your build doesn't need them now, they reward future runs through permanent unlocks.
Mid Tier — Take When Build Aligns
| Room | Drop % | Why | Skip When |
|---|---|---|---|
| Antechamber | 1.0% | Master Key + Crown access. Required post-Room-46. Guide. | Before Day 4 (you'll die) |
| Aquarius | 0.9% | Wrench item (free utility doors). Pipe layout. | Already have Wrench |
| Pump Room | 0.8% | Mine Layer 3 unlock. PSI guide. | Already solved |
| Chapel | 0.8% | Cross item (death prevention). Bell sequence. | Already have 3 Crosses |
| Trophy Room | 0.7% | Display 5 trophies = +1 inventory slot permanently. | Don't have trophies |
Low Tier Rare — Situational
| Room | Drop % | Why | Notes |
|---|---|---|---|
| Conservatory | 0.7% | Music puzzle → Piano Key item (opens piano-locked doors). | Niche use case |
| Music Room | 0.6% | Three-note melody puzzle. Pairs with Conservatory. | Without Conservatory it's just Coins |
| Atrium | 0.5% | Skylight reveals weather state. Affects 4 other rooms. | Cosmetic-feeling but lore-relevant |
| Wine Cellar | 0.5% | 4-bottle date puzzle. Reveals vault hint #2. | Skip if you know Vault code |
The 0.4% Sanctum
The Sanctum is the rarest room in the game. Datamine confirms 0.4% draw rate — about 1 in 250 daily draws. Most players never see it across an entire save file. What it does:
- Single-use room. Once drafted on a save, removed from pool.
- True Ending lever. Contains the third of three levers needed to unlock the True Ending sequence in the Antechamber.
- If missed, gated forever? No. After Day 30, the Sanctum's 0.4% bumps to 5%. The game knows.
If the Sanctum appears in a draft, you take it. No matter what your other two draft choices are. The Sanctum is the most consequential single draft choice in the game.
Rare-Tier Draft Priority Order
When two rare rooms appear in the same draft (uncommon but happens roughly once per 12-day run), the priority order:
- Sanctum — always.
- Vault — if Day 3+ and you have ≥1 Key.
- Laboratory — if you haven't mixed Formula 3 (Key Draft) yet.
- Greenhouse — if you haven't bloomed the White Iris on this save file.
- Antechamber — if Day 5+ and inventory contains a Cross.
- Observatory — Day 1 only, otherwise mid-tier.
- Everything else — situational. Default to the one whose puzzle you can solve fastest.
The Anti-Streak Mechanic
The game tracks how many days since your last rare draw. After 8 consecutive draws without a rare, the next draw is weighted +5% toward rare. After 12 days, +10%. This is invisible in-game but consistently observed.
Practical effect: if you're on Day 7 with no rares yet, Day 8 has a noticeably elevated chance. Plan your day's Step budget knowing you might draft a rare and need extra Steps to navigate to it.
Rare Rooms FAQ
Can rare rooms appear on Day 1?
Yes, with the same 15% combined chance. The Day 1 draft is not weighted differently. The Observatory on Day 1 is the best possible Day 1 draft.
Do drafted-but-not-built rare rooms persist?
No. If you draft a rare room and don't place it, the room returns to the pool. You'll get another chance.
Do rare rooms re-spawn after being built?
Most do. The Sanctum is the exception — single-use per save. Vault re-spawns but its rewards diminish (5 Sapphires first time, 2 thereafter).
Does the rare-tier list change in NG+?
No. Same 14 rooms, same drop rates. The save-file permanent perks carry over but room weights do not.
Related Guides
Room Tier List
S to D ranking across all rooms, not just rares.
See tier listShop Rooms Strategy
The other thing rare rooms do — they buy you Coins.
Read moreDay 1 Strategy
Why drafting rares on Day 1 is risky.
Day 1 plan