If Hello Kitty Island Adventure generated the same gross revenue on the Epic Games Store, Sunblink would keep approximately $5,256,938 - that's $1,170,737 more than on Steam.
At this revenue level, Epic's concrete platform fee would be $580,492. Epic charges 0% on the first $1 million in annual per-app revenue and then 12% on the remaining amount. On GOG (30% cut), the developer would earn approximately $4,086,201.
Note: This is a hypothetical comparison. Actual sales volumes differ significantly between platforms, and Steam's larger user base typically drives substantially higher sales.