🏯 A Japanese developer has built a complete Sengoku-era strategy game that runs entirely inside Vim. Not a toy, not a proof of concept. 41 provinces, 32 clans, tea ceremonies, imperial court politics, and siege battles you fight with the h, j, k and l keys.

Type :Sengoku and it is 1560

The project's formal title is Sengoku Fūunroku: Unify Japan in Vim, but the name that circulates is 「Vim長の野望」, Vimnaga no Yabō, a pun that pulls the "Nobu" out of Oda Nobunaga and drops Vim into the gap. Nobunaga no Yabō is the Japanese name of Koei's Nobunaga's Ambition, the historical strategy series that started in March 1983 and has been running ever since.

Install it as a plugin, open Vim, type :Sengoku, and a map of Japan assembles itself out of ASCII boxes. Each box is a province with a number, the clan that holds it, and its troop strength. Mutsu and Dewa sit at the top, Satsuma at the bottom. Floating panels overlay the map to show who controls what and what just happened to your army. The README asks for a terminal at least 115 columns wide and 40 rows tall, because the map alone is 110 columns.

1560 is the year of Okehazama, the battle where Oda Nobunaga ambushed a far larger Imagawa force and went from regional curiosity to national problem. Nothing on the map has been settled yet.

Generals who can only work once a month

You pick a clan. Nanbu in the far north, Shimazu in the far south, or any of the other 30. Take all 41 provinces and you have unified Japan. Lose your last castle and you are finished.

Every clan comes with its lord plus 7 historically real retainers, which works out to 256 named figures. The Oda roster runs Nobunaga, Shibata Katsuie, Kinoshita Tōkichirō (the future Toyotomi Hideyoshi, still using his original name in 1560), Akechi Mitsuhide and four others. The Shimazu get all four of the famous brothers. The Saika mercenaries of Kii province start with 80 matchlock guns, which in 1560 is a frightening amount of firepower.

One turn is one month, and each general can be assigned exactly one job per month. Your roster size is your action budget. Developing farmland, boosting commerce, handing out tax relief, conscripting troops, drilling them, leading an army, carrying a diplomatic message: every one of those costs you a general for the month. Two stats decide how well it goes, one for war and one for administration. Send your best administrator to develop farmland and your best fighter to lead the attack, or swap them and watch both jobs go badly.

Tea utensils, court rank, and a blueprint from 1990

The repository description names its model precisely: 信長の野望・武将風雲録, released in December 1990 and sold in North America as Nobunaga's Ambition: Lord of Darkness. That fourth entry in the series is the one that added technology, culture and the tea ceremony to what had been a game about farming and fighting. The Vim version keeps all of it.

You can send an envoy with 1,000 gold to the imperial court in Kyoto and be granted a rank, climbing 7 steps from Jugoi-no-ge up to Kanpaku, the emperor's chief regent. Holding Yamashiro province, which contains Kyoto, improves your odds by 30 percent. Once ranked, 2,000 gold buys an imperial mediation that forces any clan into an alliance whether they want one or not.

Scattered across the map are 10 historically famous tea utensils. Matsunaga Hisahide begins holding two of them, including the Hiragumo kettle he is said to have destroyed rather than hand over to Nobunaga. Merchants from Sakai occasionally turn up offering to sell you another. A high culture score raises your commercial income, your discount at the trading ports and your diplomatic success rate. And when you wipe out a rival clan, you take their tea collection.

Foreign trade with European merchants runs through 5 ports: Sakai, Hakata, Funai, Hirado and Bōnotsu. They sell matchlocks in bulk, imported curiosities, and cannon. A cannon costs 800 gold and needs 1,500 soldiers to haul it into the field, which makes it a decision rather than a purchase.

Sieges switch the screen to a separate castle map. Up to 5 units per side, 30 in-game days, gates with 120 hit points and walls with 200. Each unit moves 3 steps a day using hjkl or the arrow keys, which happen to be Vim's own movement keys. Either that is elegant design or it is the entire reason the game exists.

2,371 lines, zero dependencies

All of this lives in one file: plugin/sengoku.vim, roughly 90 kilobytes, 2,371 lines.

It is written in legacy Vim script rather than the newer vim9script, which looks like a step backwards until you see what it buys. The same file runs on Vim 8.0 and on Neovim. No Python, no Node, nothing compiled. Windows users can drop the repository straight into their plugin folder, a route that Impress-run software site 窓の杜 walked through when it covered the game on 27 July.

There is even a test harness. Running :SengokuTest checks the map for consistency, verifies that province adjacency is symmetrical, then simulates 36 months with every clan run by the AI and no human player at all.

Worth knowing if you plan to fork it: as of 4 August 2026 the repository carries no license file. The code is public, but the terms of use are not stated.

Playing inside the tools you work in

Takayoshi Saito posted the game on X on 25 July under the hashtag #ゆるハック, roughly "casual hack." 窓の杜 picked it up two days later and reported that the X post was what set the attention going. As of 4 August 2026 the repository sits at 86 stars and 2 forks.

This is not the first time someone in Japan has put a game somewhere it does not belong. The same site reviewed a Three Kingdoms strategy game that ran inside Microsoft Excel back in July 2010.

Wanting to add a clan or rebalance a general's stats means opening 2,371 lines of Vim script and reading them, which is a far more appealing way into the language than any tutorial has managed.

Every developer culture seems to grow its own version of this. What is the strangest thing you have found running inside the tools you use at work?

References