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Designing the challenging traversal of physics platformer Deepest Sword

How Cosmic Adventure Squad came up with the idea of traversing levels by swinging a sword and designed a world that forces players to use those swings in clever ways.

Joel Couture, Contributor

October 7, 2021

11 Min Read

Challenge is woven throughout the dungeon delving and dragon slaying world ofDeepest Sword. The novel physics platformer puts players in the role of a young knight armed with an unwieldy sword on a quest to take down a draconic foe. Only the sword isn't purely for dragon slaying. The heft and momentum of that swinging blade plays a key part in the Deepest Sword's challenging platforming as players use must practiced swings to propel their knight across hazardous terrain and toward their goal.

Game Developer spoke with Vu Ha, Rose Peng, and Johan Soriao, developers of the challenging game, to talk about how they came up with the idea of traversing levels by swinging a sword, the thoughts that went into designing a world that would force players to use those swings in clever ways, and the challenges of building the sword-swinging mechanic.

What inspired you to tie movement to swinging a sword around?

Ha: I knew we wanted to make the sword get longer and longer as you played the game, so I wanted to have a mechanic that took advantage of that aspect somehow. As I was prototyping the movement I thought, “What if we can use the sword to bridge gaps and reach further platforms? It’s easy enough to make the sword reach the other side of the gap, but how does the knight actually use that to get across?” Since we were working in 2D, I figured rotating the sword around the player made the most sense and this naturally led to this kind of circular swinging motion that enables the knight to vault over distances. It took a lot of tuning and playing with physics to actually make it so the sword could grip surfaces and climb the way it does. Once I got it working, I knew it felt unique and fun to execute.

Originally, the knight was actually able to jump, but I decided to remove jumping so that the game could be more focused on puzzle platforming. By removing the ability to jump, we narrowed the player's movement set and made it so the player had to engage with our core mechanic rather than rely on traditional platforming knowledge. This also made it easier for me to design different stages since I could focus purely on designing puzzles that used the sword climbing mechanic and reduced the number of variables I’d need to tune to make the puzzles feel satisfying.

What thoughts went into creating the sword-swinging move mechanic? In creating the finer details of dropping out in mid-swing, using the pivot for momentum, etc? In giving players options within their swing?

Ha: Deepest Sword’s sword-swinging mechanic is heavily physics based. The knight and their sword are connected and have different weights associated with them. Moving the knight moves the sword, and moving the sword moves the knight. I had to carefully tune different weights, sizes, friction forces, bounce factors, and rotational torque to create the current mechanics feel. Each sword is not only longer than the previous sword, but also feels heavier, affecting your center of balance and how much it affects the knight’s movements.

I think the feeling of weight is what really makes the mechanics stand out. Early on, I experimented with having the sword rotation tied to mouse position, similar to Getting Over It, but to me, that made the game lack a sense of weight and made the controls too finicky. Using buttons for rotating clockwise and counterclockwise brought back that feeling of heaviness, especially with the longer swords. Watching people play, you can see them press physically harder on keys and feel the knight’s struggle as they lift themselves up onto ledges. I think this level of immersion makes the game much more engaging and more fun to master.

What thoughts go into creating the game's various areas so that they provide challenges for players through the mechanics? In making platforms that will push the player's ability to use the sword movement mechanic?

Ha: Each area of the game is associated with a particular sword length, so I first had to make sure there's a clear path for that sword length to get through. From there, each area focuses on 2 things: a movement mechanic and an environmental theme. The first sword focuses on the basic movement controls and the dragon’s lair, the second sword focuses on climbing and the theme of tunnels, the third sword focuses on mastering momentum and the theme of platforms, the fourth sword focuses on mastering pivots and vaulting and the theme of zig zags, and the fifth sword focuses on reach and the theme of verticality. For the last stage, I also wanted the player to use all the skills they’ve learned so far and really show mastery of the mechanics.


Additionally, I also wanted to make sure that players would feel the differences in the sword lengths through the environment design. I wanted players to have to approach old areas slightly differently with each sword. One example of this is at the very beginning when you get the second length sword, you realize it’s hard to jump the gap so you take the lower route, but when you get the third length sword you can now take the upper path since your sword is longer.

Another example of this is when the player gets the length 4 sword, most players at this point will have been dragging their swords behind the knight, but at the entrance to the cave the player will realize they won't be able to swing their sword around to climb the initial platform. Instead, the player will have to learn how to move with their sword positioned in front of them in order to enter the cave more easily.

I would replay the different stages over and over with each sword length and adjust the level to provide different challenges, block certain paths, and open up others. I also got other people to play the areas and observe how they approach things, see where they got stuck, and adjust the level based on what I saw.

What drew you to add the different lengths of the sword? What do you feel they added to the game?

Ha: Deepest Sword was originally made for the Ludum Dare 48 game jam where the theme was “Deeper and Deeper”. We wanted to incorporate the theme in our game’s mechanics, environment design, objective, and lore. We brainstormed a lot of ideas, but the idea of a knight trying to kill a dragon by stabbing it in the heart really stuck out to us. We thought: what if the knight can’t kill the dragon because they can’t stab their sword deep enough. What if, in order to stab it deeper and deeper, the knight had to try again with a longer and longer sword, and what if the dungeon also became deeper and deeper as well?

From there, we had to figure out what it even meant to traverse a dungeon with a really long sword and that’s how we even came up with the core game mechanic. We figured the different sword lengths could be used to create interesting puzzles and slowly teach players more and more advanced mechanics.

Peng: We had a lot of fun with interpretations of the “Deeper and Deeper” theme, and the reason for the longer sword tied to a central narrative we had of a little knight having trouble stabbing a giant dragon, having to extend their sword in order to stab the sword in deeper the next run. It was hilarious so we kept it going, extending the length of the sword to ridiculous lengths and coming up with suggestive phrases for the dragon to comment on the sword with


Deepest Sword requires great expertise with its systems to play well. What do you feel draws players to games with very challenging mechanics?

Soriao: I think when players feel the challenge of mechanics as more against themselves (“if I can just do this right, I can absolutely pull this off”), it becomes more motivating and rewarding to try to master them. It’s kind of a different feeling than the challenge of a puzzle, where once you know what to do, you’ve defeated the designer. Challenging mechanics are both a puzzle you solve (“how do I do this?”) as well as something you have to repeat the performance of every time you get to that point. Mastering something that you used to struggle with feels good.

Peng: Our team has created over a dozen game jam games over the years, and always wanted to push for more replayability to encourage players to come back over and over again. In the early days of testing the sword-swinging mechanic, I thought it’d be interesting to add a gameplay timer so we could compete with one another internally since we’d have to play it a lot for testing purposes, but it quickly caught on. There’s a delightful sense of accomplishment and mastery that comes with running into a problem over and over until you are not just overcome it, but you master it and gloat to everyone else about your skills.

The mechanics of sword movement can also inspire some creative solutions to its platforming solutions. Have players found some means of using the weapon to move in ways you didn't expect? What creativity have you seen from the player base to deal with your challenges?

Soriao: Yes. One of the ones that really impressed me was a lower path skip on Sword 4. Watching players swing upwards to catch height and catch ledges in midair really impressed me! Working with the speedrunning community, we’ve even had to come up with a “No skip” category to follow our “intended path” through the game since players had found some pretty creative places to hop over ledges.

Did the game's design shift much over development? How did Deepest Sword change from its inception to the end product?

Ha: Originally, we thought of making the game more like a traditional action platformer with enemies and environmental hazards. After we prototyped the core mechanic, we realized that just traversing the environment was really fun, so we decided to refocus the game to be more of a puzzle platformer.

Additionally, I had published the game early during the game jam and surprisingly it went fairly viral on Twitter. People really latched onto the dragon’s design and the kind of suggestive dialogue in the game. Instead of being scared away by the response, we decided to lean into it. We had some time before the end of the game jam, so Rose was able to create a really awesome end screen that tied everything together.


The game seems to have some similarities to Getting Over It. Was it an inspiration? If so, how did you try to build upon the concept and make it your own?

Ha: None of us have actually played Getting Over It, but we knew about it and had seen YouTubers playing it before. I have a lot of respect for Bennet Foddy and his games, though, and was definitely inspired by the genre of difficult-to-master platformers.

After landing on the general mechanic for Deepest Sword, I did watch a few videos of Getting Over It to see how they approached some of its platforming problems, but ultimately the mechanics are actually quite different. We had to approach designing Deepest Sword in unique ways to fit the specifics of our mechanic.

In Getting Over It, the player can’t move without using their hammer; they can push off surfaces with the hammer to essentially jump around, and they can latch on to surfaces using the end of the hammer to fling themselves around. The hammer’s handle actually doesn’t have any collision, making it easy to hook it onto different things. The game controls are purely mouse-based.

In Deepest Sword, you can move your character freely left and right, the sword feels solid and heavy and gets in the way as you traverse spaces, and you’re more taking advantage of the sword’s length and friction to pivot and vault yourself to move around. The button-based mechanics make it feel closer to classic 2D platformers.

Additionally, Getting Over It is intentionally punishing as a way of making a statement. We wanted Deepest Sword to be difficult, but much more approachable and feel like a puzzle platformer, so we made sure that players always felt like they were progressing and we provided checkpoints to soften the difficulty and frustration a bit.

Peng: When we initially came up with the idea for the game, the mechanics were very different. We had jumping and moving, while the sword-swinging came in a bit later. As the mechanics evolved, it started to feel more and more familiar and we thought “Oh, this is starting to feel like Getting Over It!”. Although none of us have actually played it, we were familiar enough with the game to know we’d be getting comparisons. But the mechanic we had felt really fun and pretty different, as Vu pointed out above. In fact, we feel pretty honored to be compared to such a beloved game.

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