How much content does infinite mode have?

Ah, procedural generation. The easiest way to add replay value to a game. Or is it?

Let’s talk about content and replay value, two vague but still useful measures of entertainment. (Note: Richard Stallman published a style guide telling everyone to stop calling artistic works “content.” This isn’t really important or relevant, I just find it amusing.)

The term “content” applies to most forms of online entertainment – games, movies, comics, art, and so on. The term “replay value” obviously only applies to games, because there really isn’t the same concept in other media. Sure, you can replay a video, and people do, but not as much and not for the same reasons.

Disclaimer: this post involves a lot of personal opinion and personal experience, moreso than usual.

Defining “content”

“Content” is a measure of something, but… what? (tl;dr at bottom)

Take YouTube videos. Those are widely agreed to be “content,” but does one video equal one content? No: a hundred 5-second videos aren’t a hundred times more content than a single long video. But it isn’t video length, either. A boring hour-long livestream can feel like less content than a few minutes’ worth of 5-second videos. It seems to be a combination of video count, length, level of detail, entertainment value, and (I would argue) release schedule. We’re more likely to refer to someone as a “content creator” if they release videos at semi-regular intervals.

In video games, all kinds of things count as content. Levels, characters, weapons, items, enemies, you name it. If players are excited to see more of a thing in the next update, they’ll probably call it “content.” (You may note the two media are slightly different – a YouTube video is a single indivisible piece of content, while a game is made up of many pieces of content. But I see that as an artifact of the medium. You can’t extend or modify YouTube videos after uploading, so we don’t talk about them in those terms.)

Games receive “content updates” from time to time, and one of the things players talk about is the size of these updates. The more changes made, the bigger the update. But “changes made” isn’t the metric being used. I’ve released content updates that took ages to make and still felt disappointingly small because players breezed through the levels in 15 minutes.

So… time spent? The more time you spend, the more content in a game? Well no. If that were true, idle games would have more content than any other game, followed by super-grindy RPGs. But we never talk about grinding as content; in fact, it’s almost antithetical. Idle games do have content, but the “content” comes in between grinding. When you unlock a new item or upgrade or whatever the game involves, there’s a period of adjustment, where you’re exploring the new possibilities. You have to figure out how to use this new thing effectively, and when you start to figure that out, you settle into your new grinding routine. Each new thing that makes you think is a piece of content.

So… is “making you think” the definition of content? Not quite, but it’s a lot closer.

tl;dr: I’d say the act of exploration – either literally exploring an area or figuratively exploring the possibilities of a game mechanic – is what defines content. The more time you spend exploring, the more content there is.

Defining “replay value”

Replay value is how many times you can replay a game (or part of a game) without feeling like you’re grinding. There are still some challenges to be had and discoveries to be made, even if you’ve already seen each location, item, and upgrade at least once.

At least, that’s the definition I’ll use here. Note that by this definition, replay value is a type of content. (In fact, I’m going to use the terms semi-interchangeably.) Either way, you’re exploring the game’s possibilities, and you aren’t grinding.

Defining “grinding”

Grinding is the act of replaying a game (or a section of a game) that you already thoroughly understand. It’s all about repetition and execution – you’re going to do this thing over and over again until you achieve some kind of goal.

When you fight weak enemies in an RPG to gain experience, that’s grinding. A particularly boring type of grinding, and hardly the only type. You can also grind an obstacle course, with the goal of eventually beating it. You can grind for resources by combing back and forth over the areas they most commonly appear. In rare cases, even a boss fight – supposedly the most exciting part of a game – can end up being a grind if the fight is slow or depends on randomness.

Speedrunning is (IMO) the most exciting form of grinding. Speedrunners will practice their maneuvers over and over to build muscle memory, and then spend even more time attempting full speedruns until everything comes together and they pull off all the tricks in a row. It’s a spectacular end result made possible only by replaying a game for hours, days, weeks, months, even years past the “replay value” stage. The speedrunner already found/did everything the developers intended them to find/do (content and replay value), and decided to press onwards (grinding).

To be fair, speedrunners also spend a fair amount of time experimenting, hunting for exploitable bugs and faster routes. This is a sort of exploration, not grinding, so it counts as content. It’s just content the developers didn’t intend to add.

Infinite Mode

Now that I’ve given my definitions, on to the two “infinite” modes. Both Run and Run 3 have a mode by this name, and though they’re different, I built them with the same goal: use randomness to add replay value.

Run 1’s Infinite Mode is simple. Each level is a random scattering of tiles. Not fully random – there’s a bias towards clumping together – but close enough. This produces a practically endless number of levels, but not an endless amount of content. Once you’re good enough to beat the highest difficulty, it takes only a few more run-throughs before you get used to everything the mode has to offer, and “replaying” becomes “grinding.” Ultimately, there isn’t a whole lot of content here.

In Run 3, the mode contains over 300 pre-made levels, which you encounter in a mostly-random order. This provides a much more varied experience, with each level having a distinct style and challenge. This is, unambiguously, a lot of content, and all it took was making 300+ levels by hand. Then there are a bunch of achievements that give bonus cash if you can beat levels in unusual ways, and upgrades to be purchased with this cash, and post-run statistics that provide tidbits of information on how you did. All this creates a much more replayable mode… in theory.

In practice, most of that stuff is for grinding, and therefore doesn’t count as “content” by my definition. The main culprit are the shop prices, some of which are astronomical. You’ll still be grinding for the Angel long past when you’ve seen most of the levels. This isn’t great design, and I know that, but in my defense, it’s supposed to be temporary.

Which brings us to the future of the two modes. In short, I want to add more content to both of them, building off what already exists. I want Run 1 to generate more interesting levels, and I want to make better use of Run 3’s existing 300+ levels.

The future of Infinite Mode in Run 1

For this mode, I want to start employing patterns. So many of my hand-made levels were made by creating a simple pattern, then repeating it. It shouldn’t be hard for a computer to do the same, even if it won’t do as good a job.

On top of that, adding an option to share random seeds will instantly increase add replay value. Not by adding new levels or anything; that’s what the patterns are for. No, seeds will make the existing levels more interesting to explore. Now you have more reason to pay attention to little details, because if you find an interesting randomly-generated level, you can save it for later and share it with friends.

For those out of the loop, computers rarely use truly-random numbers. Instead, they use complicated and unpredictable patterns to simulate true randomness. The mathematics are complicated, but all you really need to understand is they start with a seed: a single number serving as a starting point. And each time you start with the same seed, you’ll get the same “random” values in the same order. That would make Infinite Mode generate the same levels in the same order, down to the tile.

Well, kind of. Infinite Mode’s levels are based on two factors: randomness and difficulty. Difficulty is constantly changing based on the player’s performance, not based on the seed. You’d only get the same levels if the difficulty value happened to be the same. Fortunately, once you unlock a difficulty, you can go back and replay lower difficulties to see what you missed.

I think this will matter most to speedrunners. Now instead of each level being its own self-contained challenge, you’re playing a set of 100 connected levels, and you know them all in advance. You have to beat only about 10% of them, and the trick is to pick the easiest and fastest ones. So say you just beat difficulty 35 and jumped to 45, but you already know that 45 is annoying and inconvenient. You might choose to fall back to 44 and play that instead, even though that reduces your progress by 1 overall. That’s 100 levels’ worth of possibilities to explore, with almost no extra effort on my part.

tl;dr: I want to generate slightly better levels, and provide a way to replay ones you like. Both would add a modest amount of replay value.

The future of Infinite Mode in Run 3

I have multiple plans for this mode. I want to make the levels more interesting in and of themselves. I want to expand the upgrade system, including upgrades to income (so the Angel doesn’t take so ridiculously long). I want to arrange the levels in more interesting ways, with occasional choice points. I want more risk-reward tradeoffs.

I plan to make the levels more interesting by adding, removing, or moving tiles. The same sort of thing that Run 1 does, except less random. This doesn’t add much new content, as the levels will be mostly the same, but it’ll keep players from getting complacent.

Everything else – upgrades, choice points, tradeoffs – will be bona fide new content, and will take a lot of effort to design. Each will introduce new strategic choices, at different levels of gameplay. Tradeoffs happen in the moment, and you succeed or fail after a few seconds. At a choice point, you commit to a branch of the tunnel, and that branch determines the next several levels. It’s a higher-level decision with longer-lasting consequences. Upgrades happen before you even set out, and affect an entire run, creating some meta-level gameplay where you decide what to bring.

Each higher-level decision will affect the lower-level ones, creating more possibilities to explore. As an example, suppose one of the upgrades is a flashlight. If you bring that along, you might feel more comfortable venturing into a low-power branch of the tunnel, because you’d still be able to see a little. But then once you’re there you come across a long-jump challenge, and you decide not to attempt the jump because the flashlight doesn’t reach that far. Instead you go around and pass up that reward. If only you’d brought a mobility upgrade in place of the flashlight… but in that case would you have risked coming to the low-power branch?

tl;dr: There’s still a lot of potential to spice up Run 3’s Infinite Mode, and I plan to do it by adding game mechanics. Adding a few more levels won’t make much difference, but new mechanics will add replay value to all 300+ levels simultaneously.

What is Runaway?

I’ve been working on Runaway since (at least) 2019, and talking about it in vague terms for about that long. But what is Runaway, really?

Before getting started, let’s clear up some terminology. Runaway is a game engine, named after Run (the game series) and Away3D (the 3D rendering library). The Runway is a tunnel in Run 3 that hasn’t been released. Despite the similar names, there’s no connection.

Overview of Runaway

A game engine is a collection of code designed to help people write games. You may have heard of engines such as Unity, Unreal, or GameMaker. Haxe – the language I named this blog after – has engines such as HaxeFlixel, HaxePunk, and/or Armory. All of these are designed to serve as a solid foundation for making games, saving you the time of re-writing your physics and rendering code each time.

Which is an odd thing for me to worry about, since I’ve never been afraid to re-write my physics and rendering code, or anything else really. Each game in the Run series was re-written from the ground up, and Runaway is its own ground-up rewrite. Though it’s taken years, I’ve learned a lot each time, and I’m building Runaway because I finally feel ready to build a standalone game engine, separate from the games themselves.

Entity-component-systems

So what sets Runaway apart from all the other engines? The big difference is, it uses an entity-component-system model. This model isn’t strictly better or worse than conventional engines, but to me it feels more elegant. (And if I’m being honest, the aesthetics are what won me over.) Practically speaking, the model lends itself to loose coupling, meaning Runaway should be especially versatile.

As the name implies, there are three important pieces here:

Entities are, you know, things. They can be anything from the tangible (characters, obstacles, items) to the vague (load triggers, score trackers), depending on what components they have.
Components are properties of entities. Things like position, size, shape, AI, abilities, and appearance. Each component is a small piece of data, and entities can have as many as needed. Note that components are nothing but passive data storage. They don’t act or update on their own.
Systems run the actual code that updates entities and components. Each system looks for a certain set of components, and updates only the entities with that set.

That’s the magic of the ECS model: what you are (an entity’s components) determines what you do (a system’s code).

Alice and Bob

Let’s walk through an example to see this in action.

var alice = new Entity();
var bob = new Entity();

Right now, Alice and Bob have nothing but a unique ID (Alice is 0 and Bob is 1). They aren’t characters yet. I’d describe them as “floating in a void”, but they can’t even do that because they don’t have positions. Let’s fix that.

alice.add(new Position(0, 0, 0));
bob.add(new Position(5, 0, 0));

Now that we gave them Position components, they’re floating in an endless void, doing nothing. How about a race?

alice.add(new Velocity(0, 0, 0));
alice.add(new Acceleration(0, 0, 1));
bob.add(new Velocity(0, 0, 10));

With the addition of new components, they immediately spring into action! Bob takes a commanding lead, at a speed of 10 units per second. Alice, meanwhile, accelerates slowly at 1 unit per second. Even after 5 seconds, she’s only moving at half Bob’s speed and has traveled only 12.5 units, compared to Bob’s 50. Bob will continue to widen the gap between them over the next several seconds, but his speed is fixed. As Alice continues to accelerate, it’s only a matter of time before she overtakes him.

But where is the code for this? Alice and Bob’s positions are changing every frame, even though Position, Velocity, and Acceleration components are nothing but data. It’s because Runaway has a class called MotionSystem, that was waiting all this time for these components to show up.

class MotionSystem extends System {
    @:update private function accelerate(acceleration:Acceleration, velocity:Velocity, time:Float):Void {
        velocity.x += acceleration.x * time;
        velocity.y += acceleration.y * time;
        velocity.z += acceleration.z * time;
    }
    
    @:update private function move(velocity:Velocity, position:Position, time:Float):Void {
        position.x += velocity.x * time;
        position.y += velocity.y * time;
        position.z += velocity.z * time;
    }
}

For those unfamiliar with Haxe, these are two “functions” named accelerate and move. The accelerate function takes three “arguments”: acceleration, velocity, and time, and it modifies velocity. The move function takes velocity, position, and time as arguments, and it modifies position.

Because these functions are marked @:update, they will automatically run once per entity per frame, but only if the entity in question has the correct components. Ignore time (it’s always available), but the other arguments must match. That means having a Position component isn’t enough, because move also requires Velocity. (Just Velocity wouldn’t be enough either.)

Now that Alice and Bob have both components, the move function automatically updates Position each frame. Alice also has an Acceleration component, so she meets the criteria for the accelerate function, and therefore accelerates as well.

While the physics described here aren’t anything impressive, the important thing to notice is how easy it is to add (or not add) functionality to an entity. Acceleration is baked into most physics engines, but in Runaway, it’s totally optional.

This is why I consider Runaway to be flexible. I can write extremely specific code, tailored to all kinds of specific situations, and then pick and choose which to apply to which entity.

Runaway’s current status

As of 2021, Runaway is being used in a single game: Run 1’s HTML5 port. It has all the features needed for that simple game, and a few more, but it’s also missing things I’ll need going forwards.

One of the improvements I need to make is the loading system. The current system requires pre-determined levels, such as the 50 levels in Run 1. But Infinite Mode generates levels on the fly, with difficulty based on your performance in the previous level, and that requires something more flexible.

I do hope to release the engine at some point, just not for a while. First I want to complete multiple games, including at least one not in the Run series, to be sure it’s stable and versatile enough to compete with the existing engines.

Status update: summer 2021

Lately, I’ve been focusing on low-level engine changes, such as “how things get loaded.” I’m building Runaway (the engine) to be as general as possible, with an eye towards reusing it in future games, and perhaps also releasing it. (Though I realize there are more than enough game engines out there already.)

When I finish the loading code, my next target will be restoring Infinite Mode to Run 1. The currently-released load system prepares levels well in advance, but in Infinite Mode, each level is generated based on your performance in the previous one, so I need to be able to fine-tune loading.

After that, my plans include, in no particular order:

Some quick gameplay changes for Run 1.
Some not-so-quick animation changes for Run 1.
Rewriting Run 2 for Runaway, which hopefully shouldn’t take long.
Rewriting Run 3/Run Mobile for Runaway, which is going to take a while but still needs to be done by November. Fingers crossed!