How Rusted Moss devs teamed up to create physics-based grappling hook action

blog.playstation.com:

Rusted Moss is an action-exploration game developed by solo individuals (not part of any development studios) that revolves around its unusual method of traversal: an absurdly bouncy grappling hook. We won’t lie: the physics-based grappling will bring you both great pain and great joy. But the triumph once you master it — you’ll practically fly through the game while blasting enemies with your arsenal of guns when Rusted Moss comes to PS5 on June 20.

In this melancholic world, humans prepare for an invasion by capricious fairies from another realm. You play as Fern, a changeling determined to put an end to the war. As you uncover the story behind the world, you’ll eventually choose a side: fae or human? 

With the PS5 release, we are also adding in seven to eight hours of additional content — approximately as much content as the base game itself. This includes new zones (ranging from moderate to very difficult), a boss rush, and an additional playable character.

During a show-and-tell with indie developers, Emlise (the main dev) showed a grappling hook that worked like a bungee rope or rubber band. She performed incredible, crazy maneuvers that made traditional platformer abilities like double jumps and dashes seem so limited. I had never seen anything like that — grappling hooks in most games either just pull you to the anchor point or swing the player in static arcs. 

It looked so polished that I was sure she would develop it into a full game. But she had no plans to. She saw it as a programming exercise to learn about verlet integration (a numerical equation used to calculate trajectories). 

“Players would find it too difficult. It takes some time to get used to,” says Emlise.

Each of us then carried out our duty as friends and peer-pressured her into continuing development. My sister and I also joined her, forming our 3-person development team. It was strange because we had no intention of making a game together before that moment. 

Rusted Moss was made to bring