Irreversible Events Considered Harmful


A conversation in OtherSide’s Discord channel the other day got me thinking about irreversible events – developer-created game situations that are like one-way doors, such that once they occur they cut off the player’s access to some previously available locations or resources. At the time, I threatened to do some writing on this subject.

Done. :smiley:

The nicely-formatted version is up now at my Gamasutra blog:

But I thought I’d also drop a slightly simplified version of it here, because I think it’s directly related to some things OtherSide are trying to do with Underworld Ascendant (and perhaps future games). I welcome your thoughts on this.


What’s An Irreversible Event?

Imagine a single path between two areas. The path leads to a collapsed ledge. You jump down, then find that the path above is too far up to reach again.

Another example: imagine crossing a bridge over a wide chasm. Every place you’ve visited so far can be reached again if you stop, turn around, and go back. Instead, you cross the bridge, but as you reach the far side, the bridge behind you crumbles and falls away. You’re now stuck on this side; there is no mechanical means in the game by which you can return to the previous side. None of those areas can be reached now.

Yet another example: you’re creeping through the dark when you hear a chitinous rustling somewhere ahead of you. You don’t want to make a light, but you have only one potion of Night Vision remaining that you wanted to save for later. You decide it’s more important to stay hidden, so you quaff the last Night Vision potion and carefully evade the nest of spiders now visible. Later, you can hear multiple skeletons clattering in the dark ahead. To avoid running into them, you must make a light. The skeletons see you and attack, forcing you to enter combat instead of enjoying being sneaky.

One more example: your character is having a conversation with another character. You’re playing your character as cool and smart, trying to keep future dialog options open with this other character. But in clicking on a speech option, your finger slips and you choose an aggressively physical response option. The character you were talking to gets angry at you, walks away, and will no longer talk to you for the rest of the game. Because the developer provides no way to reload from a recent save, you’re faced with the choice of either losing hours of play or missing out on what might be a fun interaction with an interesting character. (In a visual novel you might just replay the whole game to see the “missed” content, but let’s say here that this interaction was just one small but interesting part of a much larger RPG.)

The Squishing of Opportunity Space

What irreversible events such as these have in common is that they foreclose options. Where prior to an irreversible event there might have been 100 different things the player could choose to do, after such an event there might be only 50 possible actions, or 10, or in extreme cases only one. The opportunity space for fun has been shrunk.

Certainly not everyone will find this objectionable. But there is a subset of gamers who will object, because an important source of fun for them in games is in being able to demonstrate their cleverness. They have the most fun when a game enables and encourages surprising-but-effective choices or creative combinations, or allows them to use their pattern-detection gift to perceive a particularly good option out of a mass of possibilities. When instead a game is designed such that there’s only one (obvious) solution to each problem, or in which a mere handful of worthwhile mechanics exist that can’t be combined, there’s little opportunity for cleverness. These players will know they’re being marched through the developer’s predetermined story.

That’s not a mentally interesting game. It may be an exciting experience; or it may be a moving experience; or it may be a low-stress way to pass some time. But it’s not an most appealing kind of fun for gamers who prefer interactive entertainment that exercises their brains as well as their hands and hearts. For some gamers, less choice is less fun. And irreversible events decrease choice.

When Are Fewer Options OK?

There are some practical exceptions to this. As noted above, not every game has to emphasize thoughtful fun. It’s fine that there are games offering other kinds of fun; the gamers who like having lots of choices aren’t the only kind of gamer. If your target player prefers exciting or emotional or low-engagement fun, then keeping the possibility space limited to deliver a highly focused play experience may be the right design approach.

It also might be possible to offer too much undifferentiated choice, such as from a combinatorial system that lets players bang together hundreds of inputs to yield millions of possible outputs. (Although here I would argue the true design flaw is the “undifferentiated” aspect.) And of course implementing consumables such as food or potions is almost always a reasonable feature. Consumption as a one-way process does foreclose options, but as an economic phenomenon – a value choice – this can be a useful way of increasing the consequentiality of player decisions, which is itself a worthwhile design goal.

Foreclosing on personal interaction options with characters is trickier, but I can appreciate the argument that “this is how conversations with people in real-time actually work.” However, I’m not sure this is a strong argument for an RPG – at least, not until better AI allows NPCs to respond plausibly to surprising inputs from the player, rather than just following pre-written branching logic no matter how narratively bizarre and mechanically undesirable those character reactions may seem from a player’s perspective.

More importantly, story beats in general will usually need to be one-way. It would be extremely interesting to find a game that’s designed – not just by implementing save/reload, but through a first-class gameplay mechanic – to allow the player to backtrack to any previous story events to explore different alternatives! Short of this, it’s pretty reasonable that once the player has triggered a plot point, then short of reloading a savegame there’s no going back from that story event or its directly related consequences in the game world.

(This points out an interesting difference in the kinds of irreversible events: events in time, and events in space. Irreversible events that lock off currently existing physical or systemic spaces are IMO a Bad Thing for exploratory fun. But irreversible events that occur sequentially in time are necessarily, in virtually every case, desirable as one-way processes because that’s usually how story works.)

Player Ingenuity Is Scary… And Worth Supporting

Overall, then, with the exception of story beats it seems to me that a pattern of implementing or allowing irreversible events – consequences that reduce opportunities for player choice – is a big red flag for exploration-oriented gamers. It’s a warning that the developer is not actually committed to supporting player freedom and creativity in overcoming challenges and exploring the game world’s content, but instead wants to tightly control the player experience.

Conversely, it is a thrill to discover a game that visibly minimizes irreversible events, that I can see has taken pains to ensure that players can almost always backtrack to any location or non-story state. When I play a game that’s careful not to foreclose my options, I know it’s made by a developer who is confident in the high-level flow of the game, who is genuinely delighted when I discover a new way to interact with the game world, and who respects my fun-finding autonomy.

If you’ve built a world that’s worth exploring, why not allow and maybe even reward backtracking?


I’m not typically a fan of games that limit my autonomy using scripted events. That up to, and includes, interrupting gameplay for cutscenes. However, changing gameplay parameters can be fun, if it rewards playing in new ways, or against a new ruleset. Substantially, I think such gameplay changes should be served to explore new options, never to limit past options. For instance, flooding an area with water means the gameplay state of the area changes. Can you cast spells underwater? Are there currents? Can we freeze the water we’re swimming in? Those are open-ended questions, the point being the parameters of gameplay change, but the options do not narrow or altogether diminish.


Fair points. If what the player gains from a one-way world state change is greater than what’s lost, then maybe it’ll feel fine once the extent of the gains are realized.

To extend your area-flooding example, if it’s just a limited area that gets flooded, and I’ve fully explored every inch of that area already, then flooding it to gain access to new areas may be completely reasonable. In fact, I know I’ve played games before where flooding a space was actually a necessary step to progress through the level – I usually didn’t mind. (Dark Forces 2: Jedi Knight comes to mind, and probably Redneck Rampage as well. And BioShock?)

Even so, it’s always nice when the developer lets us un-flood the area, or otherwise provides a way to make an area state-change action reversible. If that has to be prevented (i.e., not implemented) for some reason, such as a key plot point in the game’s story, that can be OK too as long as it’s not over-used.


I think we’re on the same page. Choices that change, rather than limit, options. As far as reversible, that’s tricky–sometimes there are story reasons for cutting the player off. To clarify, artificially limiting the player is still probably is still probably not the best way to push the plot. I do not mind altering game rules for a bit, but it seems unnecessarily punitive to restrict player agency.


Looking at it from another angle, closing player options is a large part of many an RPG where your actions are often about making permanent irreversible changes to the game world, inextricably tied to the story. For example, when you take out a crime lord, you generally don’t get an option to install a new one, so that you could also get to side with him and choose the evil path.

There are choices in RPGs where, if you choose to do something, it makes sense to lock in the results, or else it can feel inconsequential. And I get the sense that people generally like to feel that what they do matters (and not just in RPGs).

Also, taking things away for the player is not always bad. It can be used to reset the slate and begin with new challenges and new options – such as the player character traveling to a new continent or changing class mid-game (Final Fantasy IV). Or it can be built into the difficulty curve, as in Warcraft 3: The Frozen Throne, where the protagonist constantly loses their abilities as the game progresses.


We keep coming back to story, don’t we, as a reason for the irreversibility of something being OK.

I think the argument from consequentiality is a lot more interesting. I touched on it briefly in talking about consumables, but I think you’re right, Starker, that it really has a larger effect than that.

I’m not convinced yet that preserving player choices by keeping states reversible hurts consequentiality. In fact, I think it can be fairly argued that reducing player choice typically makes each choice less consequential. In the near-worst case of giving the player only one option, haven’t you made the player’s choices matter less? For that matter, making the player’s character take some major action in a cutscene reduces the consequentiality of the player’s choices down to approximately zero… yes, I’m looking at you, Andrew Ryan.

It seems to me that if you give the player a real choice – not something forced by the developer’s story – to either retain access to past areas or cut off access in return for some significant benefit, that now you’re dealing in real consequentiality. I don’t know about you, but assuming the benefit has real value, I’d find this a terrifically hard choice to make… and isn’t that the kind of decision-making that players will still talk about years later?


Okay, let’s say that the player has the option to kill an NPC and lose access to their services and quests as a result. Wouldn’t letting the player retain access to the services and quests make it more inconsequential?

Losing options in a game (or gaining them) has to be considered in the context of the situation and the whole game. It is not true that irreversible events necessarily have to decrease choice – typically, as some options close, others open up at the same time. For example, when you have to move to a new area and leave the old one behind, you lose access to all the old shops, NPCs, etc, but you gain access to new shops, NPCs, etc. Quite possibly more than you had access to before.

Also, when you close an option, there’s a sense of progress, of being done with it. The player can mentally mark it explored and/or finished. After a player has finished a quest, it doesn’t always make sense to let them undo the quest to keep options open. For example, in Fallout 2, the player has a choice to optimise the Gecko power plant or to sabotage it. If you let the player continuously optimise and unoptimise it, sabotage it and undo the sabotage, it adds a lot of confusion what the player is supposed to do – whether there is something else they need to accomplish, for example. In contrast, closing off an option adds finality to it. The player knows they are done with the area and can move on.