To progress through most areas of the game, you will be killing monsters. Though, sometimes, you may have to solve puzzles.
In rooms filled with monsters, you’ll usually come across a locked door that you can’t open until all monsters are defeated.
If you take a look at the HUD in the previous picture, you’ll see 2 enemies surrounding our hero.
After our hero defeats the enemies, the red line which shows the door is locked on the map turns green.
He is now free to go deeper into the Forest.