If OMORI generated the same gross revenue on the Epic Games Store, OMOCAT, LLC would keep approximately $32,582,285 - that's $5,415,565 more than on Steam.
At this revenue level, Epic's concrete platform fee would be $4,306,675. 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 $25,822,273.
Note: This is a hypothetical comparison. Actual sales volumes differ significantly between platforms, and Steam's larger user base typically drives substantially higher sales.