Making every procedurally-generated playthrough feel unique in Swords of Ditto

It’s easy to stuff a game full of content if you have the time and the budget. What’s harder is making everything feel purposeful and, in the case of procedural games and especially roguelikes, to make random permutations feel intentional and designed. 

OneBitBeyond, creator of The Swords of Ditto, wrestled with this problem while making the vibrant roguelike action RPG. The goal was to create a player experience that remained fresh and surprising, but also felt like it had consequence across multiple playthroughs and to give the universe in-game a sense of persistency and uniqueness. 

Aided by a robust toolset created by studio lead Jonathan Biddle for GameMaker Studio, the team at OneBitBeyond put certain controls on both the placement and composition of specific dungeons, as well as ensured the mood of the game changes across multiple playthroughs to keep the experience feeling fresh.

In The Swords of Ditto, you play as a hero who has three days to prepare for a showdown with an evil witch named Mormo. These preparations include killing enemies to level up, exploring dungeons to get new items, and doing quests to unlock perks and improve your abilities. After the three days elapse, regardless of whether you are ready or not, you will face off against Mormo. 

A new hero awakes...again...and again...

If you die, rather than starting again completely anew, you will simply awake one hundred years later in the body of a new hero. This means losing your items and upgrades but keeping your experience points and having your previous deeds influence the game’s world. 

“At first, we were just making a procedurally-generated game,” says Sam Robinson, level designer and sound designer on the game. “It was just going to be a roguelike. So, every time you played it, it would be different. That was the original idea. But then, at some point, we were like, well wouldn’t it be cool if there was like a persistence to what you were doing and a consequence because it was all so happy and joyful at the beginning. There was no consequence to failure and we felt that if we added that consequence, that would make players feel a lot more attached to the world.” 

If the player does fail to beat Mormo in The Swords of Ditto, the next time they play, the overworld map will change, buildings will decay, and the ambience will become darker to convey the feeling of an evolving world, one that an evil entity has ruled over for a hundred years. Characters will also become more annoyed with the player, referring to the sorry state of the world’s affairs, and the overlay will gradually become a darker shade of purple to show Mormo’s increasing influence.

A random world with meaning

This amount of variation seems like a monumental task considering the number of different art assets and mechanics to be found in the overworld. You can visit shrines to buy more time, find and open crates at the lighthouse on the beach, and chat with farmers and other NPCs to get quests. There are also houses, toy dungeons, and windmills to explore too, as well as hidden treasure, challenge zones, and caves to interact with.

It was the personal toolset that Biddle created for GameMaker that allowed the team to do this in such a timely manner and to create so many permutations and alter assets without it ever feeling random or disorganized. 

The editor he created was extremely visual, requiring little coding experience. It is also essentially part of the game itself, allowing Robinson to switch seamlessly between the editor and the game and place a number of assets, before tying some instructions alongside them, like the potential color of items, the types of decoration, and the placement of paths. This toolset is an extension of an in-game level editor that the team actually created and shipped with Stealth Bastard, a Curve Digital game where users could create and share their own levels.

“It’s fairly controlled,” says Robinson. “There are ten layouts of the town and they randomize slightly. We have a very simple editor. It’s really cool. Bidds makes all the tools for me. I could put a building in one place and put the same building [somewhere else]. So, like two supermarkets. Then I can have a randomizer that links to both of them and I can say only one of these will exist. It’s really visual. I can just place things around and choose which one will spawn and it automatically deletes the rest. It’s like I get all these art assets from the artists, and it’s like a collage basically.”

Enter the dungeon

There is also a lot of variety in the dungeons too. There are three toy dungeons, not including incidental areas, that you can complete to unlock new weapons and perks. These include a golf dungeon, a laser ring dungeon, and a drone dungeon. The order you must complete these trials in changes with every new playthrough however, with the required level of entry and the difficulty also increasing. 

As if that wasn’t enough, the actual layout inside the dungeons changes too and there are new rules every time you enter, which modify the effect of certain items and the amount of damage you can absorb. This was achieved through a system that pieces together individual template rooms. Robinson looked at old 2D Zeldas and other adventure RPG games to determine these sizes, before implementing them in the game.

“All the variation was added to the game to ensure that players would have a different adventure each time they played. Because the dungeons, overworld, modifiers and pickups you find will be different each time, you'll never get quite the same play through twice. We basically wanted to make a compact RPG experience that someone could go through relatively quickly, but repeatedly, and find new things every time.”

The impact of this on the player is that every time they load as an original character, a new challenge will await them. This helps to sell the player on the passage of time, as the world itself feels like it has been rebuilt and new shrines and temples have been created to replace the old ones. 

The importance of dual use

The level layouts and different permutations throughout the world aren’t the only aspect that are integral to making each playthrough feel unique. The team also applied some acquired knowledge from their time working with the publisher Nintendo of Japan on Fluidity and Fluidity: Spin Cycle, incorporating the design principle of dual use into the game – something popular within The Legend of Zelda and the Super Mario games.

Designing a dungeon in layers

“Something that always stood out to me was that if you have a switch that does one thing, if you just give it another use -- not just a switch, but any other game mechanic or gadget – if you give it more than one use, that is going to create a multitude of possibilities and applications,” says Robinson. “It will give you puzzle mileage and combat mileage.” 

There are lots of examples of this throughout The Swords of Ditto. For instance, Robinson points to the golf club, which can be used to stun enemies, knock back monsters, and solve puzzles in dungeons. It also applies to other items like the drone too, which can be used to solve puzzles, but also to explore an environment ahead of time.

During each playthrough, it is extremely difficult to find all of these items in the allotted three days or gather enough cash to buy them directly from the game’s equivalent of a weapon store -- the toy shop in town. These multiple applications therefore make each item you find extremely satisfying to wield and provide a range of possibilities, rather than just being a way of simply powering up your character. 

In many ways, the approach that OneBitBeyond took on The Swords of Ditto feels like a logical expansion of the roguelike, in that it borrows extensively from more linear experiences like A Link to the Past. This approach wouldn’t normally be efficient, considering the sheer amount of coding required, but with the easy to use interface of their own map and level editors it became far more achievable. 

“It was a case of incrementally adding things just to see how far we could push it,” says Robinson. “I think we pushed ourselves pretty far. It didn’t even feel like work. It felt like a hobby, you know. Because now we’re working from home, it feels like I’m back in my teenage years. Back in my bedroom just making levels for other people’s games. Except now I’m making my own.”