SEGA historically enforced strict copyright takedowns, but JSK’s games were mostly left untouched. Why? Because they were free, non-commercial, and kept the Sonic brand alive during a dark period for the franchise. Many argue that SEGA tolerated UFS because it reminded fans why they loved the blue blur in the first place.

While JSK produced several demos and tech tests, two titles defined his legacy.

JSK’s philosophy was simple: replicate the momentum-based physics of the SEGA Genesis titles, but wrap them in original level designs and a distinctly Flash-era aesthetic.