Background Despite the increasing popularity of exergame practice and its promising benefits in counteracting physical inactivity, limited research has been performed to document the physiological responses during an exergame session. This study aims (i) to investigate the responses of heart rate (HR) and oxygen uptake (VO2) during an exergame session and to compare with HR and VO2 measured during joystick session and (ii) to compare HR and VO2 obtained during exergame and joystick session with those HR and VO2 associated with first and second ventilatory thresholds (VT 1 and VT 2 , respectively) obtained during a maximal graded exercise test. Methods A total of 39 participants performed a maximal graded exercise test to determine maximal oxygen uptake (VO2max), VT 1 , and VT 2 . On separate days, participants performed an exergame and traditional sedentary game (with a joystick) sessions. The time that participants remained with HR and VO2 below the VT 1 , between the VT 1 and VT 2 and above the VT 2 were calculated to determine exercise intensity. Results Heart rate and VO2 were below VT 1 during 1,503 ± 292 s (86.1 ± 16.7%) and 1,610 ± 215 s (92.2 ± 12.3%), respectively. There was an increase in HR and VO2 as a function of exergame phases, since HR mean values in the ‘warm-up’ period (119 ± 13 bpm) were lower than the ‘main phase’ (136 ± 15 bpm) and ‘cool-down’ periods (143 ± 15 bpm) ( p < 0.001). Regarding VO2 values, the ‘warm-up’ (25.7 ± 2.9 mL.kg ⁻¹ .min ⁻¹ ) were similar to the ‘main phase’ (25.1 ± 2.8 mL.kg ⁻¹ .min ⁻¹ ) ( p > 0.05) and lower than the ‘cool-down’ (28.0 ± 4.8 mL.kg ⁻¹ .min ⁻¹ ) ( p < 0.001). For all times of the joystick session, average HR and VO2 were below the VT 1 levels. Conclusion Exergames can be classified as light to moderate exercise. Thus, exergames could be an interesting alternative to traditional forms of exercise