In this update v0.13, enemy's design was changed and the difficulty was adjusted.
From the 7th basement floor, there are enemies that revive. They had something worm-like. However, it was not satisfactory for me. With this update, this has been replaced with a more Japanese design.
There have also been significant changes to the design of the enemies that appear after the 8th basement floor.
There are also changes to the difficulty level. In the previous version, the visual distance was decreased from 10 meters to 6 meters. As a result, the difficulty was slightly increased. Therefore, various changes have been made to decrease the difficulty level. Check out the list below for more details.

Changes of enemy design

- Enemies that revive
- Enemies that appear after the 8th basement floor

Difficulty

- Enemies that revive will be knocked down by one head shot.
- Changing the enemy's visual distance from 8 meters to 6 meters. 6 meters is the same with player's visual distance.
- Change the number of enemies called by the nurse call from two to one.
- Changed the number of enemies called by surveillance cameras from two to one.

Bugfixes

- Bug: A enemy goes away that calls with nurse-call.
- Bug: Enemy's bullets go through walls sometimes.

Spoiler! This image shows new design enemies.