In this paper we report on an affective gaming interface and a user study which evaluates user response to affective gaming. “Feed the Fish” is an affect-aware game system which takes a player’s facial expressions as input and dynamically responds to the player by changing the game elements. The goal of this system is to use human expressions to build a communication channel between the game and players so playing the game can be more enjoyable. We describe the implementation of the game system and discuss the result of the user study we have conducted with 22 participants. Participants enjoyed the game with the affect-aware system more than a non affective version of the game, and they felt it was more exciting since the game was more challenging and dynamic.