Teaching lessons about determination
This is a very mature game. Players will be fighting fantasy creatures such as dragons, living skeletons, and undead. However they will also be fighting some monsters that are very sexualized (one particular boss is part spider part naked woman, and her breasts are barely covered by her hair).
The game has a predominant theme of hopelessness and existential crisis. Many casual people will not understand the story, but the more curious will be given a story about despair and how all things have to eventually come to an end. A deep yet morbid theme.
This game above all taught me to stay determined. Bosses are extremely tough and can kill you in a single hit, so you have to learn their patterns through trial and error. The game teaches that observation is key to understanding something. Through its combat and explorative gameplay