Most escape games and related experiences are designed for groups and marketed as quality time or teambuilding.  However, it’s easy for a designer to take for granted that their game rewards and inspires teamwork.  In the many games I’ve played and constructed, I’ve seen challenges that successfully foster teamwork and those that failed to.  In this article I’ll share a few principles that will hopefully stimulate your design imagination to bake more teamwork into your challenges.
2 traps to designing for teamwork
Many of us assume that including a variety of types of challenges will foster teamwork.  Surely a room with a math puzzle, a word puzzle, and a visual puzzle will require teamwork to succeed.  Of course variety is good but it doesn’t necessarily create teamwork for two reasons.  First, people usually play rooms with their friends or coworkers who are pretty similar to them, not with a hand-picked team of specialists.  Nurses play with nurses, engineers with other engineers.  Second, ‘cover all the bases’ variety can allow players in diverse teams to silo themselves, individually focusing on challenges they’re already most familiar with.

Another low-effort way we’ve all tried to compel teamwork is with sheer volume. This can vary from a large number of puzzles to big piles of data that it takes multiple people to sift through.  These rooms punish smaller teams, leisurely paces, and disorganization after the fact with failure, but don’t do anything to actually reward teamwork during the experience.  Often these experiences have the boiler room vibe of an SAT test, calling for a breakneck pace and significant team effort in project management and organization.   This strategy also harms the storytelling potential of your room: too high a volume pressures teams to skip challenges if they’re able to and limits you to one pace throughout the experience.

Compelling Coordinated Action
While those approaches are precarious and limiting, challenges that require simultaneous, separated interactions compel teamwork in a more reliable organic way.  By simultaneous I mean occurring at the same time and by separated I mean unable to be performed by the same person. For a simple example, a puzzle that requires two distant buttons to be pressed at the same time requires two coordinated players.
The surefire way to compel teamwork is through challenges that require coordinated group action.  Such challenges must require multiple players’ involvement simultaneously.  If the challenge cannot be solved by one super-intelligent player, then it’s going to foster teamwork.  These upcoming principles all help, and are organized least to most challenging.
I haven't seen a pure feat of strength in an escape game yet but I hope I do some day.  
4 Principles that build teamwork into challenges
  • Cumbersome objects that require multiple people to manipulate may seem like a hack way to inject teamwork but I’ve seen them be very fun.  In a simple example of this from the Bay Area, markings on a large sheet line up to markings on the wall of the room.  It takes two people to hold up the sheet and another to interpret the markings from far away.  These types of challenges create physical fun and involve those who aren’t “puzzle people.
  •  Separated controls that need to be actuated simultaneously additionally require planning and coordination at a distance.  For instance, 5 momentary buttons scattered throughout the room need to be pressed all at the same time and no one person can reach two buttons at once.
  • Separated stimuli that need to be received simultaneously require coordination from teams and get players calling out information at each other.  For instance, two separated telephone receivers hear alternating words of a long code phrase.  Two players repeating aloud can combine the phrase.
  • Separated controls and feedback are the most challenging and require the most effective communication. For best results, use controls whose feedback is fleeting or tasks that require immediate feedback.  The classic magnet maze is a great example of this one: one player sees a maze and the other can move an item through it using a magnet.  These are most exciting in situations where the moving player has never seen the maze layout.

Plenty of professional jobs have specialized roles built into them, like sniper and spotter (an instance of separated controls and feedback).  To bake teamwork with unexpected specialized roles into a game you need to telegraph your intentions to the players.  
A Caveat
Challenges that require teamwork require more obvious prompts than individual puzzles because players need evidence to persuade their team to follow a line of thought.  I played a game recently where a puzzle solution asked the entire team to stand in a tight space.  One player refused, unconvinced by the logical leap the rest of the team had made.  While one player could try several unclear possibilities out of curiosity, they need evidence to break the social hurdles to ask someone else to help them.

Conclusion

These principles for compelling teamwork offer clear ways to transform creative designs and reactive room elements into memorable group experiences.  These sorts of challenges create experiences with friends and family, not just beside them.  Since being together in a physical space is a key differentiator of our experiences from other games and puzzles, let’s really design experiences that make use of people working together.