Connect puzzle elements -- During playtesting, we quickly found that puzzle elements which required no action or consultation from the other player often fell flat. Ensuring that elements require a verbal and/or physical input from the other player has helped cut out these flat parts. In the case of the lock, we maintained this by distributing part of the code sequence to each player, requiring them to communicate to uncover the entire code. We realized that in order for Shackle's unique layout to work, all puzzles would need to be deeply integrated with this structure in mind.

Facilitate memorable dialogue -- Since players can't see each others' experiences, they should be easy to communicate and also worth sharing. We first discovered this when we decided make the lock's combination a subtle reference to a well-known song on a whim. It typically led to some comical, calming discussion between players among an otherwise suspenseful and frightening experience.

Make understandable objects -- In order for players to collaboratively solve puzzles, they need to be able to accurately describe their environments to one another. When an object's perceived functionality doesn't match its actual functionality, it makes solving the puzzles difficult for the wrong reason. Early on, we found that most players weren't picking up on the fact that the desk drawer could be opened. By redesigning the drawer's model with a bigger handle to better afford pulling, we were able to effectively squash this misconception.

Cleverly present instructions -- With virtual reality's recent and expensive introduction to the market, we've found that most of our playtesters haven't experienced VR firsthand before. This means most are easily amazed by the initial experience - just looking around is entertaining. As a result, our in-game attempts to explain controls and gameplay were often overlooked. To make sure players know how to interact with objects like the lock, we landed on displaying tips like this:

Cleverly present instructions (cont.) -- By showing the entire controller when displaying controls, it allows players to feel around for the necessary input rather than having to take the headset off and look at the controller. Additionally, these tips only dismiss themselves once the associated input has completed, thus confirming that players understand the tip, and ensuring it doesn't dismiss itself before they see it.

Never stop learning -- Exploring a new design space is exciting, but it can also be daunting. What's important is that we've found success amidst our playtesting, showing that our concept has potential. Uncertainty aside, we're excited to continue exploring this new design space and launch Shackle!