More and more studios are realizing it's not worth it to create and maintain their own engine, and training new hires for the studio's proprietary software, when they can just pay Epic 5% royalties and spend more of their time on the games themselves, which is the same process indie devs go through because they are focused on making a game first. Unreal Engine is one of the few engines with decent off-the-shelf documentation in Japanese and Sonic Crossworlds is already using it. With rising costs and time being money, the days of in-house engines are coming to an end. It would be a miracle if Hedgehog Engine 2 lasts 5 more years