This paper explores the adaptation of traditional platformer games into casual exergames for breaking up prolonged sitting periods during workdays. We present Platformer, a browser-based casual exergame that incorporates established platformer design principles while integrating physical movements through webcam-based detection. The game implements three key design patterns (guidance, safe zones, and pace breaking) and requires both upper and lower body movements during two-minute gameplay sessions. An exploratory single-case pilot study conducted over 1.5 weeks (N = 100 play sessions) revealed preliminary trends suggesting potential increases in both game performance and physical movements over time, though with varying movement patterns across different body parts. While limited by its single-case nature, this study provides initial insights into adapting traditional video game genres for workplace health interventions and suggests directions for future research in casual exergame design.