X_SiiMMo_X has the exact same appearance as Steve.
Not much is known about his personality, but we can assume that he is a Noob, as he fell for a "Free diamonds" button trap.
5 Ways to Make Someone Rage Quit
X_SiiMMo_X makes his first and only appearance in this video. He first walk into a room with a button and a sign saying "Free diamonds!" above. This excites SiiMMo, s he pushes the button. This causes a cluster of primed TNT to spawn around him, making him blow up. Then, we can see a message in the chat, saying that SiiMMo left the game.
- 5 Ways to Make Someone Rage Quit was the first machinima TNT has ever done, and X_SiiMMo_X was the first character in the video. This makes X_SiiMMo_X the first character to ever appear in TNT's machinimas.