Moonmilk Games is developing Cave Expedition, a Unity caving simulator for 1-4 players. The developers are cavers themselves and want to capture what it feels like to move through narrow passages with ropes and equipment.
Getting the ropes right proved difficult. Fredrik explains that a rope made from many connected rigid bodies can become unstable when something touches it. The team moved away from Unity's built-in physics for the ropes and chose Obi Physics.
In Obi, a rope is made of particles connected by constraints. These are rules that control how the particles move relative to one another, keeping them connected while allowing the rope to bend.
Fredrik describes this approach as much more stable than a rope with the same number of rigidbody segments.
The switch also affected the player. To get the rope interactions they wanted, the team built the player's body in the same physics system, along with other physical elements in the game.
That required more than setting up the ropes. They had to substantially extend the system with basic functionality they would normally get from Unity's built-in physics.
- Game: Cave Expedition on Steam
- Developer: Moonmilk Games
- Reddit: Original gameplay post
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