Trojan Knight
The Greeks were in the middle of war around 3000 years ago. In a smart attempt to destroy their opponent from the inside, master carpenter Epeuis built a massive and hollow wooden horse. He planned to put his soldiers inside the horse, And offer it as a peace bearing to the enemy. If the unknown goddess had accepted this harmful gift, she would soon have hundreds of enemies swarming the inside of her palace. And of course, they took the bait and the Greeks would win that battle.
Since chess is a replica of war, can we use this 3000-year-old trick in chess? I think that we can. Once a king castles, it makes an impenetrable fortress around the king, using pawns and rooks as walls. If you send in a trojan horse (or knight in this scenario) to break open the enemy fortress, then you can send in your other troops into the attack and soon overthrow the castle.
Instead of playing 4...Nxe4, this leads to a very well known and well hated berlin variation, black moves the "trojan knight" over to the fortress that white has created. White naturally wants the knight out of there, so they play 5...h3, but the knight will not move, as it is probably a few hundred pounds of wood with more weight of the soldier inside it. Instead, black sets up the trap by going 5...h5!!
