Interactive games may boost positive well-being by combining the benefits of rewards with cognitive and social enrichment. However, a hasty introduction can lead to low success and frustration. We examine two methods of introducing an interactive game to dogs to test whether they elicit differences in success rate, stress-related behavior, and autonomic regulation of the heart. Twenty-eight shelter dogs were tested with an interactive game that consists of four boxes with different opening mechanisms. Dogs were introduced to the game in one of two ways: gradually vs hastily. Gradual introduction consisted of allowing the dog to first play a partial (2 out of 4 boxes) version of the game with a human demonstrating the opening mechanism of the boxes twice, followed by exposure to the complete game. Hasty introduction consisted of the same procedures but with the complete game presented before the partial version. Dog behavior was obtained via video recordings and pre- and post-game mean heart rate (HR), its overall variability (SDNN), a measure of parasympathetic activation (RMSSD) and their balance (RMSSD/SDNN) were assessed using beat-to-beat intervals obtained with a Polar heart rate monitor (RS800CX). Linear mixed effects analyses (LMM) were calculated for success and behavior component scores and for change from pre- to post-game period in HR/HRV variables. In addition, HR/HRV parameters were analyzed with Pearson correlations. Dogs introduced to the game in a gradual manner had a significantly higher rate of success (LMM: p < 0.001) and displayed less stress related-behavior, e.g. lower scores for the arousal (p < 0.001) and displacement (p<0.001) components. Correlation analysis revealed a negative correlation between HR and RMSSD during baseline in all dogs (pre-game, day 1: gradual: r = -0.52; hasty: r = -0.72) that transformed into a strong positive correlation in the gradual introduction group (post-game, day 2: r = 0.78), whereas it remained negative over all evaluation periods in the hasty introduction group (post-game, day 2: r = -0.83). Overall, our findings suggest that the way a moderately difficult game is introduced plays a major role in determining how the experience is perceived. A gradual introduction including demonstration promoted a more enjoyable experience characterized by greater likelihood of reward, less stress-related behavior, and a physiological profile that may involve activation of both branches of the autonomic nervous system. We suggest that this may be a physiologic signature of successful achievement in which skills are balanced against difficulty.