This is a classic!
This is a well-known pasta. Plot changes should not be added until information has been released by the author.

The story of green Steve goes like this:

I was playing Minecraft on the 1.8 update when I found a desert temple, like most players I broke the blue block and jumped down the hole. I accidently hit the block that sets off the TNT but, surprisingly, it did not go off.

A Steve-like mob came down from the hole where the blue block was and it looked like Steve, only green. It hit me and I appeared in a room made of bedrock filled with creepers I was really freaked out so I exited.

I then went back then next day. To my surprise, I was not in the creeper cave but in a forest. It was like I had made a new world, though I obviously hadn't.

Strange enough, the chat box popped up with the words: "<Green Steve> I am coming." This was very weird. I double-checked to see if I was on Multiplayer, but shockingly, I wasn't. I moved through the forest, still wondering about the chat message.

In a few moments, I happened to stumble across a house. It had been my house in the world before only in a forest not a desert. I went in.

There was nothing. Then the green mob came in. Another message appeared in the chat box: "<Green Steve> Hello brother."

Then I just blew up, having no idea what had happened. I deleted the world it after that, because I didn't want to come across this weird entity again. I sent an email to one of the developers who had helped in the making of Minecraft about my experience, and he replied, "One of the developers wanted to added Green Steve to Minecraft, but we said no and we had caught him adding it in." If this story is true it could explain Herobrine and many other things.

Someone talking about the green steve story in less detail.

The green steve is a minecraft creepypasta. the story is that a player claims to have met a beast (green steve) that tried to kill him in a desert temple. Afterwords he claimed to have an email from a video game maker who said that they wanted green steve in the game but everyone else said no and he was found try to hack the game. If this story is true this could be what every minecraft creepypasta like Herobrine really is.

Another story

The story of the green steve goes like this:

I was playing minecraft when i found a desert temple and i went inside. I broke the blue block and jumped down to get the stuff. I hit the plate but it did not blow up. instead a weird mob came up to me. Its skin was green other then that it looked like Steve. It tried to kill me. I briefly battled it until it shot a dark block at me and I was sent to a room of bedrock filled with creepers. I was pretty freaked out so i turned off the game the next day i emailed a video game developer who had helped make the game and he said that a developer wanted to add it to the game but everyone else said no and he was fired for adding it in the game! If this is true then this could explain Herobrine,null, and many other things.