TL;DR: Hollow Knight is mainly characterized by dual-purpose design and general minimalism. A particular feature is the use of fluid builds based on charms that can be (un)equipped rather than a skill tree. However, changing builds can be too much blind trial and error while geo (the game’s currency) becomes too abundant too early in the game. One solution to this could be having the player pay geo for (un)equipping charms.
Hollow Knight is the story of a nameless bug who explores the depths of a fallen kingdom, thereby slaying countless foes with his nail and uncovering the history of the mysterious place as well as his own fate. It is a Metroidvania type of game released in 2017 and—as far as I’m concerned—one of the best (if not the best) installations of this genre so far.
One factor that makes this game so great is that it builds a lot on the concept of dual-purpose design. Dual purpose design, as the name suggests, means that one game mechanic serves two different purposes, e.g., Super Mario’s jump, which is used for platforming as well as defeating enemies. If you want to learn more about this concept, Mark Brown made a video about it for his awesome channel Game Maker’s Toolkit, from which I draw a lot of my design inspiration.
Apart from that, Hollow Knight also generally employs a rather minimalistic approach. There are only two weapons in the game and the primary weapon—the nail—can be upgraded a total of only four times. When you hit enemies with the nail, you take HP from them and at the same time gain soul (dual purpose!). Soul is used for both, healing and using one of the three spells you can collect during the game. This simple set-up has two particular effects that make Hollow Knight exciting: First, during fights, you have to decide between healing and attacking with the powerful spells. Second, when low on health (which is very limited) and out of soul, you are forced to risk approaching enemies and hitting them.
The second resource in Hollow Knight besides soul is geo, which is the kingdom’s currency. Since there are no health and magic potions to be bought (because soul), geo is exclusively used for purchasing items that let you advance in the game or make you more powerful (such as mask shards, which upgrade your health Zelda-style). Therefore, geo is essentially experience.
Finally, one of the most distinguishing features of Hollow Knight is the lack of a skill tree. Instead, you buy charms. These give you certain powers and upgrades—such as an increased nail range or a shield—and can be equipped and unequipped every time you rest on a bench. The number of charms you can equip at the same time, however, is limited. Charms make your build fluid, so unlike in similar games (e.g., Salt and Sanctuary), you don’t have to decide for or against a certain build early in the game. This is one of the strengths of Hollow Knight because you can (and have to) use wildly different strategies for each boss. Yet, in my opinion, it is also one of the games few weaknesses since equipping and unequipping charms before boss fights is too much trial and error and too little “living with the consequences”. The last boss fight didn’t work out? Just throw in some other charms and try a face tank. Didn’t work either? Don’t worry, I got some more charms for you!
Now, how would it be possible to prevent this? Let’s have a look at two potential solutions. As for the first one, I think a relatively simple design change could do the trick. What if (un)equipping charms would cost geo (starting with the second time a charm has been equipped to still facilitate some playing around)? This would solve two problems at once. First, it would prevent the blind trial and error with different builds. Second, geo becomes too abundant too early in the game. At the very beginning, you still have to pay some attention to your balance, but later, you just buy all the upgrades you can find and still have plenty in your bank account. The second solution could be simply reducing the amount of charms, but make each charm more impactful, and making geo less abundant—that would be more like the Cuphead approach. Less charms, less trial and error. Pretty straightforward, isn’t it?
However, there is a another issue. The excessive trial and error is not only caused by the sheer number of charms and the fact that it comes at no cost but also the often not really informative descriptions of what a charm can do for you. That is, a charm’s capabilities are not visible until trying it out, also in different combinations. Therefore, the above solutions would only work if the game had a way to better visualize the certain powers and advantages of charms. This could be achieved by, e.g., showing a little loop animation of your character performing all the actions possible with your current build plus the charm that you would add to the selection.
In conclusion, despite some little flaws, Hollow Knight is awesome. However, it is not just an awesome video game. It is also a lesson in good design and how “less is more”. I believe that every designer—no matter their focus—can learn some valuable lessons from this game—and from good game design in general.
Special thanks to Martin and Snuck for their valuable feedback.