Space Oddity: Deconstructing the curious design of Gravity Ghost

Ivy Games' lush 2D space physics puzzler Gravity Ghost wears its nonviolent nature on its sleeve, but creator Erin Robinson says it has its roots in one of the earliest shooters ever made: Asteroids.

Speaking today about lessons learned from Gravity Ghost's development during GDC's Independent Games Summit, Robinson explained that her most recent game -- which garnered critical acclaim when it launched on Steam in January -- started as an Asteroids clone she began building years ago as an excuse to practice programming.

“But at some point I thought gosh, wouldn’t it be cool if I could land on a planet and plant some trees?’” said Robinson. Inspired by games like Eufloria, she began experimenting with gardening mechanics in games.

But Gravity Ghost really gained its own unique personality when Robinson tried eliminating the spaceship and simply letting the player character — a cloaked young girl — hop from tiny planet to tiny planet planting trees and terraforming the galaxy.

“I put a lot of art polish into it without doing my due diligence to see how fun it was,” said Robinson. “Unfortunately, terraforming turned out to not be that much fun.”

She says that “proved to be the biggest false start in development” of Gravity Ghost, and terraforming was eventually dropped from the game.

But beloved concepts and mechanics have a way of sticking around. 

While Robinson had to give up her original idea of terraforming planets, she later drew inspiration from it to design a mechanic where players can spend energy — visually identified as the character’s hair — to solve puzzles by changing planet types (from a fire planet to an ice planet, for example).

Other ideas worked right away during development, including planets with physics systems ("people love to see little planets crashing into each other with physics") and mazes that you navigate through by playing with the game's gravity mechanics.

Robinson recommends that other developers embrace player feedback during the design process; many of the smaller successful aspects of Gravity Ghost's design were inspired by watching people play prototypes. 

“I just kind of try to learn by watching the playtesters,” said Robinson. “I like to see what they do.” 

For example, Robinson noticed that players naturally enjoyed walking in circles around Gravity Ghost's miniature planets — so she took time to develop a mechanic that rewards them for doing so.

This sort of reactive development process is also responsible for the core conceit of the Gravity Ghost narrative -- that your playing as a ghost. 

“The real turning point in the narrative was like, I thought…what if people can’t see her? What if she’s really a ghost?” said Robinson, referring to a segment of the Gravity Ghost prototype where other characters weren’t responding to the girl protagonist because they weren’t programmed to. “That gave us a narrative underpinning, and everything came together from there.”

But there were still significant development challenges to overcome.

“Level order was a difficult problem,” said Robinson. Since the levels were tied to imaginary constellations, “there really wasn’t a rhyme or reason to which level should go where.” 

To make each level interesting and determine a good order, Robinson studied 2D Boy's World of Goo.

"It’s really genius what they did,” says Robinson. “The first two levels are normal, then the third level you get this new albino type [of goo]…but then it doesn’t show up again for a while.” She sees it as a promise to the player of things to come, an ordered way to gently introduce new ideas and mechanics without confusing the player.

So Robinson went to a craft store, bought a bunch of markers and note cards and made a physical card for each level with color-coded dots denoting which types of planets and mechanics were at play.

With that, she could quickly sort through the levels they’d built and order them in a way that ensured a gradual complexity curve.

Heading into final launch, the Gravity Ghost team relied on weekly meetings, a solid bug/task tracker (PivotalTracker, in this case) and amped-up QA using a hired tester plus volunteers sourced from Twitter and reddit.

Robinson recommends other small-scale developers take advantage of communities like reddit for testing, and suggests that services like MailChimp and the PressKit() platform to efficiently get your game in front of the press in a natural, non-forced way.

"“There are ways to position your game in a way where you’re just talking about it, but in a way that makes it more enticing,” said Robinson. "That can make all the difference."