There's two different puzzles going on in this room, there's actually killing the roaches, and then there's getting all of the roaches trapped in the boxes. Trapping them in the boxes lets you head South that leads to a non-required "
secret"
puzzle room. Because this room to the South is optional, you can always come back ad figure out how to get in later by using the "
Restore"
option in the main menu.
The secret text below spoils one way of putting the roaches in the boxes if you still need more help.
Click here to view the secret text
×Enter from the West and you can very easily trap 2 out of 3 of the roaches, but the third one will run towards you. Monsters treat your sword as an obstacle and will not move onto it, so by pointing your sword towards the roach you can let him follow you closely without being able to touch you. Point your sword to the right and let the roach come towards you.
You will want to stand so that the roach will end up standing directly below the bottom-most point of the left-most box, with you standing to the left of it with your sword between you and the roach. Now move North until you are hugging the walls of he box, the roach will be standing right below you. Move around the box standing as close to the walls as you can and when you move around the top of the box the roach will get trapped behind the top-most point of the box. Now you can safely move far away and manipulate the roach into its box from a safe distance.
