An important thing with games is that all the participants are supposed to share the understanding that they are participating voluntarily in a game with specific rules. As long as gamification sticks to this, it's already somewhat separable from the field cognitive bias exploitation in general, where all sorts of subterfuge is generally the rule.

Games are obviously compelling even with the players being aware that they are participating in a voluntary game. But does gamification work even when the mechanism the game is supposed to serve some ulterior goal and the cognitive biases that it works on are made clear to the player? Jane McGonigal has described running gamification on herself, and apparently being successful with it.