Levels in Games for Health.

There is a time-honored procedure in games for pure entertainment wherein games challenge their players by offering successfully higher levels of difficulty. An eminent researcher proposed that player engagement and enjoyment require the player being constantly challenged, but at a level she or he can handle. A game's difficulty levels enable the player to face more difficult challenges as she or he builds gameplaying skills. Although levels work in games for entertainment, it is not clear how effective or important levels are in games for health, or how they are designed. We invited several accomplished games for health designers and researchers to discuss levels.