Marie's Adventure ALTOMYOSTR Floors F1–F4

ALTOMYOSTR is the late multi-floor challenge dungeon referenced by four Steam achievements in Marie’s Adventure: Explorer (F1), Delver (F2), Conqueror (F3), and Master (F4). Global unlock rates sit near the bottom of the 69-trophy list, which tells you this is a completionist gauntlet — not a tutorial cave.

This page is a routing and prep guide, not a spoiler-heavy room-by-room map. Pair it with Combat Basics, Party Progression, and the Achievements roadmap.

Why ALTOMYOSTR matters

Floor trophy	Achievement name
F1	ALTOMYOSTR Explorer
F2	ALTOMYOSTR Delver
F3	ALTOMYOSTR Conqueror
F4	ALTOMYOSTR Master

Clearing all four floors is independent of the pregnancy engine, but the dungeon still interacts with it: every hallway you walk advances active pregnancies. Entering F3 while Marie is at 95% without a Sylva plan is how completionists soft-brick their mental state.

Entry assumptions

Community and Steam trophy ordering place ALTOMYOSTR after early story and mid-game combat spikes. Before you commit:

1. Unlock the full party when possible — Marie plus Elucia and Ran for skill coverage and heal redundancy.
2. Finish at least one clean birth power-up cycle at Sylva City Inn so the roster is not still on tutorial stats.
3. Stock healing food and battle items; F2+ assumes you understand turn order from Combat Basics.
4. Manual-save in Sylva (or another safe hub) before the floor gate — separate from your multiples-hunting slot.
5. Confirm content toggles will not skip scenes you still need elsewhere (content settings).

Floor-by-floor mindset

F1 — Explorer

Treat F1 as a skill check on your current kit. Learn enemy telegraph patterns, do not burn every consumable, and leave with a save after the floor clear popup / trophy. If F1 already feels brutal, go farm demon routes and another birth cycle before F2.

F2 — Delver

F2 raises density and punish windows. Focus fire priority targets, keep a healer action ready, and avoid greed pulls in corridors that resemble Desert Caves chokepoints. Wipe recovery costs walking time on any pregnant heroine.

F3 — Conqueror

Expect multi-phase or endurance fights. If any heroine is past ~80% pregnancy, strongly consider leaving for Sylva before pushing the floor boss. Overdue inside a deep floor is a worse soft-lock than postponing the trophy.

F4 — Master

F4 is the prestige clear. Bring maxed artifacts where relevant (artifacts), know every character’s skill list for the mastery trophies that overlap this grind, and keep a teleport / exit plan if the game provides one for the dungeon wing.

Pregnancy calendar inside ALTOMYOSTR

Pregnancy state	Recommendation
Not pregnant	Ideal for deep pushes
Under ~60%	Acceptable if you pack heals
60–90%	Short floor attempts; exit before bosses if unsure
100% / overdue	Leave for Sylva Inn immediately

Walking rules never change underground. Birth still only triggers at Sylva — see How to Give Birth.

Achievement cross-links

ALTOMYOSTR clears stack with other late trophies:

• Demon Hunter / Demon May Cry — kill counts while you farm approaches.
• WORLD REPOPULATION SQUADRON FULL POWER! — learn every skill on every character.
• No Stone Unturned / Old World Testament — treasure and artifact collection often shares late-game routing.
• Marie’s Adventure — meta 100% that includes these floors.

Full trophy table: Achievements.

Practical session plan

1. Hub save in Sylva.
2. Check pregnancy % and milk capacity (pregnancy tracker).
3. Enter one floor with a hard stop time — do not binge F1→F4 if anyone is near term.
4. After each floor clear, return to hub, save, heal, reconsider belly status.
5. Apply latest www hotfix if a boss event soft-locks (known issues).

Related pages

• Build Hub — combat and progression index.
• Combat Basics — turn fundamentals.
• Party Progression — birth power spikes before deep floors.
• Achievements — trophy checklist.
• World Locations — overworld context.

ALTOMYOSTR rewards patience more than heroics. Clear one floor per session when pregnant, deliver on schedule, then come back for Master.