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L’Empereur — the two-tier turn: KOEI’s NES→SNES design hinge

KOEI’s 8th NES strategy title (computer 1990 / NES 1991), decompiled to the bank. Read as software, L’Empereur is a transitional specimen: the same family engine and start-of-turn skeleton as the earlier NES conquest sims, but with a new country→province two-tier turn that the 16-bit titles would formalize. Grounded in LEmp-decompiler (all 18 code banks named).

Links: How KOEI’s NES AI & combat evolved (the five-decompiler study this extends structurally) · The Hollow Opponent (the shallow-AI reading it sits beside) · repo LEmp-decompiler → docs/03-completion.md. Engine finding reused: the [[project_koei_e2e3_native_trampoline]] native-call ABI.

The finding: two command phases, not one

Every KOEI NES conquest sim opens a turn the same way — a start-of-turn events + monthly upkeep pass (L’Empereur: bank 17 advance_turn → calendar roll → scheduled events → the seasonal per-country/ per-city batch: tax, food/materials, starvation, officer aging, disasters). That skeleton is family-invariant; it is the shared spine every title in the line inherits.

What L’Empereur adds is a split in the action phase that follows. Bank 1 (the $8000 turn/command library) runs two separate loops with two separate cursors:

Country / strategic phase — iterate the 15 countries in turn order (table $6FF2, cursor mem_6FF0); for each whose ruler general_can_command, run sub_8039 (mem_76A2 = the country, $7068+). Here live the country-scoped commands: diplomacy (bank 5), national give / ceremony (bank 4’s distribute_food_all / cmd_hold_ceremony), the info screens (bank 6).
Province phase — a fresh city turn-order table is built (sub_90A4(0x7002, 46)), then iterated (cursor mem_6FF1); for each city whose governor can command, run sub_80C0 (mem_7CD1 = the city, $7176+) — recruit / develop / arrange / etc.

Country phase first, province phase second — and the computer plays the same shape: sub_AC1C (ai_run_country_turn) runs scripted-event → ai_choose_diplomacy (country) → ai_run_turn_actions → ai_run_domestic_loop (cities). The earlier NES titles are flatter: you drop straight into per-fief / per-officer orders with no distinct national tier. This country tier is the structural move — a layer of decision above the map — that the SNES conquest sims (RoT3K III+, the 16-bit Nobunaga titles) formalize. L’Empereur is where it first appears in the NES line.

[interpretation, flagged] We have only decompiled the NES corpus; the SNES alignment is an informed read of the design lineage, not a decompiled comparison. What is code-confirmed is the two-phase loop itself (two cursors mem_6FF0/mem_6FF1, two order tables $6FF2/$7002, two dispatch subs).

Simplifications and retentions

Tax is now a command, and thin. [confirmed] It is a per-city policy flag (+27, bit &32) set by cmd_set_policy (bank 4); the turn engine’s collect_tax_income (bank 17) reads that flag and auto-converts commerce → gold. No variable rate, no loyalty-penalty curve like Nobunaga’s tax dial — a binary policy plus automatic collection. The knob became a switch.
Orders still ride on officers, not just provinces. [confirmed] The officer-holds-an-army model is family-invariant back to ROTK1 (game 1): cmd_arrange distributes soldiers/horses/guns onto officers (+9/+10/+11), and a battle unit is an officer + army. So there are two allocation layers — the per-turn national order budget (mem_705F = 2, set at the top of each country turn) and the per-officer army — which is exactly the texture you feel: commanding generals, inside provinces, inside countries.

Branding and setting

Dual branding, GemFire-era. [confirmed via ROM strings] The title screen carries the ASCII company brand **KOEI (bank 0) and Press Start Button (bank 16); the L’Empereur production title itself is a CHR-tile logo (not ASCII). The opening is a scripted Napoleon cinematic — Vive l'Empereur, Josephine (“wife of Napoleon”), “Brave soldiers, follow my command! I will lead you to victory and fame!” This is the same present-the-company-brand-plus-the-localized-title packaging GemFire uses (US “Gemfire” ⟵ JP “Royal Blood”); by game 7–8 KOEI is fully into that dual-label habit.
The period is the run-up, not just the wars. [confirmed] The engine’s year base is 1790 (age_in_officers gates officers on year − 1790), so scenarios open in the revolutionary window before Napoleon’s ascent — the game models the European conditions that produced him, which most players know far less well than Austerlitz or Waterloo. A deliberate, and unusually didactic, framing.

Where it sits in the arc

The AI/combat study reads the five earlier decompilers and finds KOEI experimenting, not climbing a single upgrade curve. L’Empereur adds a structural datapoint to that story: the studio was also experimenting with the turn container — and here it lands on the two-tier country→province shape the 16-bit generation would keep. Same engine, same start-of-turn function, one new layer of decision above the map. A hinge title: last of the NES conquest sims, first with the SNES-era turn architecture.