Interesting article here.
Steams 30 cut is actually the industry standard
"Another source also stressed that just because a retailer takes 30% doesn’t mean the developer of the game actually gets the other 70%, saying publishers often earn between 30-70% of a sale themselves depending on the deal that has been struck. There are also engine licensing fees to consider (games that use Unreal have its 5% fee waived if they are sold on the Epic Store), taxes, and other costs not factored into what many people assume the actual creator of a game earns. One source said their takeaway from a physical retailer at the end of the day is often between just 10-15%."
So my guess is that if this game had been sold on steam, instead of 3.6 you'd have...
Drumroll please!
(100-25*.18*0.7)*(4-5)$=-96.85$