Specific phobias like spider phobia represent a frequent mental health problem in children and adolescents, demanding innovative prevention and treatment approaches. We therefore develop an eye tracking supported Virtual Reality serious game for school-aged children, realizing gaze interactions to promote attention towards, and positive experiences during exposure to spiders. Within pilot studies in adults (n=30) and children (n=14) without fear of spiders, we assessed positive and negative affect during prototype gaze feedback through five different variants: If gazed for few seconds, the virtual spider changed into a shrunk, a rainbow coloured, or dying spider, or morphed into a smileyball, or speaks friendly. We found the highest positive affect for the rainbow and smileyball variant, followed by the shrunk and friendly speaking variant. In contrast, the dying variant was excluded due to the possible induction of negative affect. Findings indicate eligible variants for the further development of the VR serious game.