The list of variables is quite lengthy. If there are just a little "off" the participants can still have good notable immersive experiences experiences but less likely to achieve full flow state.

If these variables are considerably outside of recommended parameters, then it can completely prevent anyone from experiencing flow in the game.

Again these experiments focused primarily on tabletop RPG, but are to various degrees applicable to LARP as well.

Game Master (GM) Variables

• Improvisational flexibility (versus inability to adapt to unexpected PC choices)
• Creativity (versus narrow rigidness, reading only what’s written for example)
• Balanced Intuitive Rules skills: This is far beyond just rules/system knowledge aka Rules As Written (R.A.W) knowledge which only helps to keep the game from grinding to a halt from looking up rules (important to avoid as much as possible)). These skills it include keeping the game play moving smoothly during rulings, and knowing when to draw on the rules (versus narrative, role-play or GM fiat), use the rules, bend the rules, break the rules, change the rules, fudge the dice (in favor of the PCs), versus focusing on other aspects of game play. Generally research shows overly rigid “Rules Lawyers” drive away most new and experienced gamers (95+% will quietly leave group by not showing up at future sessions), and reducing/ruin the enjoyment of RPG sessions for most players (95%+ turned off by rules discussion in-game, either taking too long discussing the rules up front starting the game, or disrupting game flow in-game).
• Experience - Trained experience (very powerful predictor), vs. Unmindful, Untrained long-term GM experience (less important the many of the other variables). Balanced Player experience with GM experience (GM’s who no longer play at fairly regularly(or at least 10% of their annual RPG time), frequently become terrible GMs over time, losing touch with the player experience, and often increasingly blaming players discontent in a campaign that are actually due to the GM’s shortcomings).
• Overall competence
• Verbal skills
• Cognitive skills
• Social/empathic skills
• Narrative style
• Acting style
• "Voicing"
• NPC richness
• World richness
• Multiple sensory adjectives
• Illusion of omniscient  DM (helpful for player enjoyment if not abused).

Adventure/Campaign Variables

• Background depth
• Sensory richness
• Sense of connectedness
• Logic of environment
• Physics

Players Variables

• Cooperative attitude
• Willingness to suspend disbelief
• Kinds of sensory "visualization" tendencies (some people can't visualize, but experience immersion through other senses)
• Interest in genre
• Interest in setting
• Interest in game complexity
• Interest in game style (combat vs. narrative vs. exploration, etc (Bartle))
• Group/Camaraderie Building Tools

The above is so subjective and difficult to specify (many papers unto themselves), but assuming a qualified GM, and cooperative players (though that wasn't always the case during these experiments, there was a little bit of a "weeding out" process of the most disruptive players that were unwilling to follow the code of conduct consistently), most of the experiments focused on environmental factors to increase the likelihood of flow experiences, that is what the majority of this document covers.

Environment & Game Variables

• Group Size
• Game Session Length
• Game Session Frequency
• Keeping party together vs. splitting up the groups
• One-shots (1 session to completion), short-shots (a few sessions to completion), campaigns (many/unlimited sessions).
• Game Setting
• Game System
• "Alignment" of characters
• "Alignment" of campaign
• Sandbox vs. semi-structured vs. "rail-roaded"
• Camaraderie building techniques
• Technology use/misuse
• Facility temperature
• Facility lighting
• Facility walls (color, maps, posters, etc.)
• Facility cleanliness
• Facility noise levels
• Public vs. private settings
• As above, but specific considerations for convention settings
• Other facility distractions (people coming-going, street traffic, sunlight beaming in, etc.)
• RPG Accessories
• Sound effects & music
• Costumes & props
• Pre and post game processing