Undying Fortress

For centuries, a mysterious fortress hovered above the kingdom of Serendal. Now it has fallen, and everything inside it, treasure, secrets, and monsters alike, is within reach of whoever is brave or desperate enough to go looking. Undying Fortress casts the player as a disgraced former student of the Imperial Academy, expelled from their studies as a knight-scholar and now scraping by as a mercenary, who gets pulled into infiltrating the fallen fortress alongside a small band of companions. Written by Yeonsoo Julian Kim, author of the earlier Choice of Games title The Fog Knows Your Name, it is entirely text-based: no graphics, no sound effects, 500,000 words and hundreds of choices standing in for every mechanic a conventional RPG would otherwise render on screen.

A fantasy world built from two traditions at once

What reviewers single out first is the setting itself. Several describe Undying Fortress as blending classical European-style fantasy, floating fortresses, imperial academies, knightly orders, with a distinctly Korean-inspired mythological framework running underneath it, something one detailed reviewer frames explicitly as "European style fantasy with a fresher Asian (specifically Korean) inspired fantasy world." That combination is treated in the review pool as a genuine point of difference from Choice of Games' broader catalogue, much of which leans on established genre templates like vampire courts or superhero academies. Reviewers who describe themselves as longtime fans of the studio's other lines, including its licensed World of Darkness titles, single out Undying Fortress as pulling them in specifically because the setting felt unfamiliar rather than another variation on a formula they'd already seen.

The prose itself gets consistent, detailed praise for its atmosphere: reviewers describe a "dark atmosphere," a story that captures "the horror vibe very well," and a sense of dread that builds as the party pushes deeper into the fortress's mysteries. One reviewer frames the whole experience as "a gruelling slog but not in a negative way," saying the game deliberately withholds any sense of relief until very late, which they credit for making the story feel genuinely tense rather than merely long.

Choices with teeth, and a save system that shows none

The mechanical core of any Choice of Games title is its branching structure, and Undying Fortress leans unusually hard into consequence. Reviewers describe deciding which of several named companions live or die, which relationships develop into romance, and which secrets about the fortress and its history the player's character is even able to learn, all of it shaped by choices made much earlier in the story. One reviewer's account of accidentally locking in a romance subplot after flirting with a different character for most of the game, only to have a later dialogue option retroactively commit them to someone else, illustrates just how far downstream a single choice's consequences can travel.

The sharpest complaint in the review pool is structural rather than narrative: Undying Fortress has no manual save system, and getting a character killed or a companion lost forces a full restart from the beginning. One reviewer calls it "one of the harder CoGs," pointing out that "choices definitely matter, and it's absolutely punishing if you make a wrong decision," and describes the resulting loop as "tiring but at the same time rewarding" once a player finally gets through the parts they were stuck restarting. That framing, hard but ultimately worth it, is echoed by most of the positive reviews, but it is presented as a real barrier rather than a minor inconvenience, and at least one player reports resorting to manual save-scumming through the Steam Cloud save slot just to avoid replaying long stretches after a bad branch.

Not every reader is won over

Not every review is glowing. One of the more detailed critical reviews, from a player who ultimately returned the game, argues the writing itself is "not poorly written; but lower scale," describing it as "very very very YA style writing" and comparing it unfavourably to the author's prior, more mature work. Another reviewer flags the primary antagonist specifically, saying her motivations and the framing of the player's options toward her feel inconsistent depending on which branch led there, even while praising the ending they personally reached. These aren't universal complaints, most of the pool is enthusiastic, but they're detailed and specific enough to suggest the writing's tone and the antagonist's characterization won't land the same way for every reader.

Achievements that map a wide but uneven web of endings

Steam's global achievement data gives a useful outside check on how players are actually experiencing the branching structure. Of the 21 tracked achievements, the most common (tied to an early, hard-to-avoid story beat) sits at 81.5% of players who have unlocked anything, while the rarest named outcomes sit under 1%. That spread is exactly what you'd expect from a story that funnels most players through a shared opening before scattering them across a genuinely wide set of possible endings, rather than a single main path with minor cosmetic variation, and it lines up with reviewers' own descriptions of reaching "a really terrific ending" that felt personally earned rather than the only ending available.

Final verdict

Undying Fortress is a confidently written, atmospherically dark piece of interactive fiction that distinguishes itself from Choice of Games' broader catalogue through a genuinely distinctive setting and a branching structure willing to make choices actually cost something. The lack of a manual save system is a real and repeatedly flagged frustration, and the writing doesn't land equally well for every reader, but the strength and specificity of its praise, particularly around its setting and its willingness to let consequences stick, outweighs those complaints for the audience it's built for. Recommended for interactive-fiction readers who don't mind restarting when a choice goes badly, less so for anyone hoping for a gentler, more forgiving structure.