If Sunkenland generated the same gross revenue on the Epic Games Store, Vector3 Studio would keep approximately $9,230,340 - that's $1,965,846 more than on Steam.
At this revenue level, Epic's concrete platform fee would be $1,122,319. 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 $7,246,862.
Note: This is a hypothetical comparison. Actual sales volumes differ significantly between platforms, and Steam's larger user base typically drives substantially higher sales.