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GDC 2016: Ojiro Fumoto on polishing Downwell’s gun boots

In his talk at the Game Developers Conference, Ojiro Fumoto spoke about the success of his mobile and PC game, Downwell, and how it was built around one core game mechanic.




In his talk at the Game Developers Conference, Ojiro Fumoto spoke about the success of his mobile and PC game, Downwell, and how it was built around one core game mechanic.

Fumoto’s original inspiration was to create a game like Spelunky that could be played on the go.

“I was, and still am, deeply in love with Spelunky,” said Fumoto. “Simply, as a gamer I wished there’d be a game that was as engaging and unpredictable as Spelunky but playable on mobile. I set out to make a game I would want to play.”


Fumoto decided from the start that the game would be a 2D platformer, playable on mobile, with vertical levels that moved downwards. It was also important that, like Spelunky, the game had some random elements to encourage replayability.

In Downwell the player descends a vertical shaft wearing boots that shoot bullets downwards. These ‘gun boots’ provide two gameplay mechanics. Firstly, they obliterate enemies in your path. Secondly, their recoil provides a way to move around the screen.

An early build of Downwell was a leisurely affair, much more like a traditional insta-death platformer, albeit one with levels that descended. Fumoto thought the execution was not particularly interesting but did see some potential in the concept that was worth further exploration.

“I didn’t even have a design document,” admits Fumoto. “So the next step was to find a mechanic that made it different.”

With the game being designed for mobile, controls were all important. Fumoto wanted to employ three inputs as a maximum, assigned to left and right movement, plus jump.

“I had played a bunch of action games on mobile before and I felt that the more buttons they have on screen, the harder the game was to control.”

In any case, with the game using a portrait orientation screen estate was at a premium. This lead Fumoto to explore the gun boots concept where jump and fire could be assigned to one button.


“The gun boots mechanic was fun, it was weird as a concept, it was definitely different as a control scheme, and it was intuitive to control,” he said.


The addition of the gun boots concept changed the game entirely. Most importantly, it served multiple purposes in terms of gameplay.

“The shooting, of course, was the offensive option but the recoil could be used for manoeuvring in mid-air. Immediately I knew this was a great mechanic that held a lot of potential,” said Fumoto.

It was a key moment in the development of the game, not least because it backed-up Shigeru Miyamoto’s famous old adage that a good idea should solve multiple problems at once.

Fumoto embarked on further refinement, testing out how to best use the new mechanics. Limiting ammo seemed an obvious way to provide challenge, but Fumoto found that it slowed the game down. He wanted to find a middle ground, so instead tried implementing a stamina system.

“Maybe a stamina system like in Dark Souls would work well, where attacking would use up stamina but it would replenish after a short amount of time,” he said. “I really wanted to make the mechanics around shooting as intuitive as possible. It’s the action that defines the game.”


Although the system worked, the wait to replenish stamina broke the tempo of the game. Realising that being forced to land was an unavoidable consequence Fumoto removed the wait entirely, allowing the player to refill the gauge every time they touched the ground.

The introduction of gun boots also had a impact on environmental design. At first Fumoto tried to make each randomly generated level as interesting as possible. As a result the game felt too enclosed and confined once the gun boot mechanics had been introduced.

“I changed things up drastically so there was a lot more space. I had way less platforms and way more floating enemies. It encouraged more motion from the player in general.”


The end result provides the player with more freedom in how they approach the levels, as well as forcing them to always be on the move.

The final addition to the experience was the implementation of a combo system. A count of consecutive enemy kills was used in an early build of the game, but subsequently removed. However once the gun boot’s recoil mechanic was introduced, Fumoto found himself bouncing on enemies in succession, just for fun.

“I had long forgotten about this combo idea but during play testing I found myself trying to consistently land on the enemies, doing the combos without the system actually being there.”

Fumoto reintroduced combos to the game, providing a higher difficulty option for more experienced players without making it something you had to select at the start of the game. It seemed like he had landed on the ideal combination, after much trial and error.

Throughout his talk Fumuto was extremely humble, preferring to credit fortuitous luck – rather than his own talent – for the game’s success. He concluded with a few words of advice about focus:

“It might be good practice in general to focus on what makes your game special and make that part shine as much as possible with the surrounding gameplay,” he said. “The gun boots alone wouldn’t have made Downwell all that special, but rather the rules and mechanics I added around it made the whole thing great.”

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Thumbsticks editor and connoisseur of Belgian buns. Currently playing: Paper Mario: The Origami King, Animal Crossing: New Horizons, and Pikmin 3 Deluxe.


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