Sins Paradise: Domination System - Chapter 25: Assassins

In short, MC inadvertently created a world, but as the creator of the world, he did not know the world at all. He should have lived here like a fish in the sea with some plug-ins that MCs always have. But now he is even stumped by the bugs in the instant world. Luckily, in this world he has found his shadow guard, or his lover? So the daily adventure is getting not so boring…

- Description from Novelupdates

In a world where beast masters rule by taming magical creatures and competing in thrilling tournaments, becoming the most celebrated sport, Eratz seemed destined for greatness. Surrounded by friends and family, his path was set until a shocking betrayal shattered his dreams.Fueled by the pain of his betrayal, Eratz looks up at the night sky, finding a new purpose. He vows to rise from the ashes and conquer the beast master world, determined to become the greatest and reclaim his lost honor.

I made a game.