Goblin Monsters

Not much is known about Goblins as of yet, however, they will appear during Goblin Invasions as seen in the gameplay trailer with the message: "Goblin army is approaching from the west/east" warning the player. Since the world is pre-rendered and everything is still running even while off screen you can make different choices on how to deal with them such as intercepting them before they arrive at your base or waiting in readiness for their arrival.

Some of them can open doors, most likely the Goblin Thieves. There is no information on what the goblin thieves are capable of yet, they seemingly can't steal from your chests. Assumingly they act as a peon and try to hit you, or possibly they just open the doors for other goblins.

Goblin Sorcerers attack from a range, and can teleport through walls. Warriors and Peons just try to hit you with melee, but they hit quite hard if they get a chance. Goblin Sorcerers have a small chance of dropping Rocket Boots.

They drop Coins, Spiky Balls, Rocket Boots, Shurikens, and Harpoons. Considering their generally high value drops, a Goblin army may be able to drop an even bigger variety of high tier items.