由 Towa Chiki 於 1989 年 5 月 1 日在任天堂 Famicom（紅白機）上推出的《名偵探福爾摩斯：來自 M 的挑戰書》，是前作《霧之倫敦殺人事件》的正統續篇。若說前作仍停留在較為基礎的推理解謎層次，那麼本作則將整體規模與張力大幅提升，直接聚焦於福爾摩斯與其宿敵莫里亞蒂教授之間的終極智力對決，成功在 8 位元主機上呈現出一場充滿壓迫感與緊張感的推理戰爭。

在整體表現上，延續前作的系統架構，但在視覺與氛圍營造方面有顯著進化。倫敦街景與室內場景更加細緻，畫面細節的增加讓整個城市更具真實感與沉浸感。同時，為了強調「挑戰書」所帶來的危機與壓迫，遊戲中設計大量由莫里亞蒂留下的機關與暗號，使玩家時刻處於被監視與操控的緊張狀態。音樂風格也轉為更加急促且帶有威脅感的旋律，營造出一種無法喘息的追逐氛圍。遊戲結構方面，不再只是單一案件，而是由多個彼此連結的小事件逐步拼湊出一個龐大的犯罪陰謀。

劇情一開始便直入核心。被稱為「犯罪界拿破崙」的莫里亞蒂公開向福爾摩斯發出挑戰，整個倫敦隨即陷入連環事件之中。從大英博物館的竊案，到高層人物收到的恐嚇信，每個現場都留下「M」的標記。玩家將扮演福爾摩斯，與華生一同在迷霧籠罩的倫敦奔走，逐步破解謎題、分析線索，並試圖看穿莫里亞蒂層層設下的陷阱。最終的目標，是在如同萊辛巴赫瀑布般的決戰場景中，徹底擊潰這位宿敵的犯罪帝國。

在操作方面，遊戲延續傳統文字冒險（AVG）的指令系統，透過「看」、「拿」、「說」、「移動」等指令進行探索。大幅提升整體難度與互動深度，尤其在「暗號解讀」方面成為核心要素。莫里亞蒂所留下的謎語與密碼往往缺乏直覺提示，必須依靠邏輯推理，甚至需要在現實中記錄線索才能逐步破解。此外，時間管理機制也更加嚴格，在倫敦各區移動時會消耗時間，一旦判斷失誤，可能錯過關鍵事件，導致劇情卡關。部分證據還需帶回實驗室進行分析後才能使用，使整體體驗更貼近偵探工作的流程。

在市場評價上，被普遍認為是紅白機時代最具挑戰性的推理遊戲之一。評論普遍肯定其高度燒腦的謎題設計與強烈的沉浸感，特別是成功塑造出「整個城市都是犯罪現場」的壓迫氛圍。不過，其過高的難度也讓不少玩家感到挫折，因為許多解法缺乏明確提示，往往需要反覆嘗試各種可能性。即便如此，仍在歷史上占有一席之地，尤其是在塑造反派角色方面極為成功，讓莫里亞蒂不再只是背景人物，而成為真正與玩家對抗的存在。

這款遊戲最令人難忘的體驗，莫過於在辛苦破解一連串複雜密碼後，畫面上卻出現莫里亞蒂帶著嘲諷語氣的訊息，讓人瞬間意識到這不過是另一層陷阱的開端。那種被對手完全看穿、卻又不得不繼續追逐的感覺，正是本作最迷人的地方。許多玩家至今仍記得，在無數次切換選單與線索之間，追尋莫里亞蒂蹤跡的那段緊張而沉迷的時光。

Released by Towa Chiki on May 1, 1989, for the Nintendo Famicom, Meitantei Holmes: M Kara no Chousenjou (Detective Holmes: A Challenge from M) serves as the direct sequel to the previous year’s London Murder Case in the Fog. While the first game focused on relatively straightforward deduction, this follow-up elevates the narrative into a full-scale intellectual showdown between Sherlock Holmes and his lifelong nemesis, Professor Moriarty, bringing their legendary rivalry to life on an 8-bit stage.

In terms of presentation, the game builds upon its predecessor with more detailed visuals and a stronger sense of atmosphere. The streets of London and interior environments are rendered with greater care, and the addition of elaborate traps and coded messages left behind by Moriarty enhances the tension implied by the “challenge letter” concept. The music also shifts in tone, adopting a faster, more ominous rhythm that reinforces the constant sense of being targeted by a powerful and unseen adversary. Structurally, the game moves beyond a single case, instead presenting a chain of interconnected mysteries that gradually reveal a much larger conspiracy.

The story wastes no time establishing its premise. Moriarty, the so-called “Napoleon of Crime,” openly challenges Holmes, setting off a series of bizarre incidents across London. From thefts at the British Museum to threatening letters sent to high-ranking officials, each crime scene bears the unmistakable mark of “M.” Holmes and Dr. Watson must navigate the fog-covered city, deciphering riddles, codes, and deadly traps laid out by their enemy. The ultimate goal is to confront Moriarty in a climactic final encounter reminiscent of the Reichenbach Falls, bringing an end to his vast criminal network.

Gameplay retains the command-based adventure system of the original, using actions such as “Look,” “Take,” “Talk,” and “Move.” However, the sequel significantly raises the level of difficulty and interactivity. One of its defining features is the emphasis on decoding ciphers and riddles left by Moriarty. These puzzles demand strong logical reasoning and often require players to take notes outside the game. Time management also becomes a critical factor, as traveling between locations like Scotland Yard, the East End, and Baker Street consumes valuable time, and missing key moments can halt progress entirely. Additionally, certain clues must be analyzed in Holmes’s laboratory before they become useful, adding a layer of scientific investigation to the experience.

Upon release, the game earned a reputation as one of the most challenging detective titles on the Famicom. Critics praised its complex puzzle design and the way it immersed players in a London where the entire city feels like a crime scene under Moriarty’s control. At the same time, its difficulty proved to be a double-edged sword, as the lack of intuitive solutions often forced players into exhaustive trial-and-error. Despite this, the game holds an important place in the history of early detective games, particularly for its successful portrayal of a charismatic and formidable antagonist. Rather than simply offering a collection of puzzles, it functions as an interactive Holmes narrative, where the player actively participates in a battle of wits.

One of the most memorable aspects of the game is the moment when, after painstakingly solving a complicated code, the screen reveals Moriarty’s mocking message—reminding you that what you’ve just uncovered is merely another layer of his elaborate trap. Many players still recall the countless times they navigated through menus and clues, chasing Moriarty’s shadow through a maze of deception and intellect.