I Gained Power in Another World, and Used It To Turn My Own To Chaos

Joshua Greene is a man without a lot of time left.

He's living day to day with a bad heart, a bad body, and over all a bad life.

But you know the drill by now, right? He finds a door and gets sent to another world. But rather than use the power he gains for good, or even for a noble cause, he uses it in the most violent ways possible, all while maintaining the air of a depressed, lonely guy little to nothing left.