While it's a common technique in literature and film, anachrony is widely seen as more problematic to use in games, perhaps even to the point of being unusable. If the player's actions during a flashback scene imply a future that differs considerably from the one already presented in a present-day scene (say, the player kills someone who they had been talking to in a present-day scene, or commits suicide in a flashback), this produces an inconsistent narrative. The root of the problem is that players generally have a degree of freedom of action, so flashbacks are less like the case in literature and film—where already decided events are simply narrated out of order—and more like time travel, where the player travels back in time and can mess up the timeline. Juul is a forceful representative of this viewpoint, arguing:
In an "interactive story" game where the user watches video clips and occasionally makes choices, story time, narrative time, and reading/viewing time will move apart, but when the user can act, they must necessarily implode: it is impossible to influence something that has already happened. This means that you cannot have interactivity and narration at the same time. And this means in practice that games almost never perform basic narrative operations like flashback and flash forward. Games are almost always chronological.
One solution could be to tackle the pitfall of incoherence as a game-design problem. Perhaps a designer can very carefully craft the player's space of action so that the player does have meaningful agency on the one hand, but all possible outcomes are coherent, on the other hand. That task might be rendered more manageable with computational assistance that keeps track of which events have already been revealed to the player as happening, and therefore must now be held fixed.
We had a more fundamental question, however: how do players react to this kind of agency-related incoherence in anachronic game narratives in the first place? Is it as fatal of a problem as widely assumed, even when it does arise? When players do something in a flashback scene that's inconsistent with a present-day scene they had already played, do they notice, and what do they think of it?
To investigate what players think when they produce an inconsistency in a flashback, a student here at ITU, Miika Pirtola, built two case-study games in which players can sometimes do things in a flashback scene that would invalidate the coherence of a present-day scene they had already played. He observed their play and interviewed them afterwards. Looking through the breadth of comments from players of these testbed games, we were able to generalize three main ways that players react to these episodes of narrative incoherence:
1. The acceptive-ludic players viewed the problem of potential incoherence during flashbacks as part of the structure of the game. Some of them thought the possibility of producing incoherence was actually part of the game goals, e.g. that they were responsible for acting in a consistent manner in the flashback, and might suffer negative consequences if they "broke" the timeline. This category of player generally saw the ability to manipulate the timeline, even in ways that may be incoherent, as a valid and potentially interesting game mechanic, viewing incoherencies as a result of their actions and their responsibility, rather than a flaw in the game or the responsibility of the designer to account for.
2. The acceptive-diegetic players assume the apparently incoherent timeline is not actually incoherent at all, but rather has a legitimate explanation. For mundane incoherencies, this is particularly easy: a smashed TV might have been carted off and replaced between the flashback and present-day scene. Even with more severe incoherencies, a diegetic explanation is always possible, though some are more farfetched than others: perhaps the person apparently killed in a flashback was really someone else, or perhaps the flashback was just a dream, or maybe the game is just now revealing a fantasy or magical element, and the person has been resurrected, or is immortal, or is a holograph. In short, this category of player assumes that anything they see was supposed to happen and has a coherent explanation, no matter how strange it may seem at first.
3. The rejective-logical players, unlike the two kinds of acceptive players, did consider the narrative inconsistency objectionable, and viewed it as an error in the game. Either they assumed it was simply a bug in the game, or that the designer had been sloppy and failed to provide sufficient explanation of what was really going on. This kind of player considers it the designer's responsibility to both make sure the narrative is coherent, and to make sure any apparent incoherencies are sufficiently explained. This player is the kind often implicitly assumed in the literature on anachrony in games: the kind of player for whom anachrony in games often ends up producing a game they consider broken, making the technique dangerous to use.
There are many subtleties that remain to be studied: we studied only flashbacks, not flashforwards. And players may react differently to different kinds of incoherence, or to rare versus frequent cases. But our study thus far suggests that a significant portion of players are acceptive of at least some cases of incoherence in anachronic gameplay, for two different reasons. Some players see manipulating event timelines out of order as a game mechanic in itself, and incoherencies as an inevitable and acceptable result of that mechanic. Others are willing to fill in diegetic explanations and give the game the benefit of the doubt, assuming that apparent incoherencies aren't in fact incoherent, but merely as-yet-unexplained. This range of player reactions suggests that game designers need not necessarily regard the potential for anachronic techniques to introduce incoherencies into the narrative timeline as a fatal flaw that makes it necessary to stick to chronological narration.