Arcadie: Second-Born

This is a Twine game narrating the story of the protagonist, you, the second prince/princess of the warmongering kingdom of Arcadie. Your parents have given you everything, but expected nothing of you. While, your sister, the heir, was the one to garner all the attention from everyone in the kingdom. The assassination of your parents leaves both of you orphans and with the heavy responsibility of dealing with the mess created from this event.

Storywise

The main story focus points are:
1.Sibling relationships: How the main character feels about their sister Ariana. Do they feel inferior to her, hate her for hogging all the attention from their parents, are indifferent or do they have a good relationship with her? Keep in mind that Ariana is headstrong and a person who is the queen first and then your sister. Expressing your distaste or disagreement with a decision she may take could lead to a not so likeable reaction from her.
2.Inner struggles: Second child syndrome, inferiority complex (optional), vengeance or forgiveness, dealing with parent's death and (Spoiler - click to show) later Ariana's death .
3. What it means to be a monarch? What path must Arcadie choose for the future?
4. Aether
5. Romance
6.Managing the kingdom's foreign relations and preparing for the upcoming siege

a) The game is more stat-oriented in action scenes but in general I would put it on the choice-based interactive fiction games category. What you have focused on learning through the years as a prince/princess will be the deciding factor on whether you are successful or not in combat and battle scenes. It also effects some choice availability in other scenes too.
b) Your choices will affect the relationships between the MC and other character around you, mainly Ariana and the romantic options. As I stated before, you should really take into consideration each character's personality before making choices and if you want to unlock a romantic route (maybe a guide could be published later by the author to make it easier for other players).
c) Costumization were neither too many nor too few, but just the right amount subjectively speaking. It was a nice touch, adding options to choose if you've inherited the eye color and/or hair color from your parents which is accompanied by some flavor text.
d) For a fantasy setting there is quite a realistic narrative of a family with a firstborn golden child and a normal second-born. And MC is reminded everyday they are less important than their sister even if they are both royals. This bothers them,as can be understood from the inner monologue, but they can choose how it affects their relationship with their parents and their sister.
e) Personally, I went with C's romantic route. and it was a very satisfying experience. They are an important commander coming from the richest family in Arcadie and a very sweet lover. You can choose three ways in how your relationship will play out, but I chose lover route, naturally (How could I choose differently?). One thing to note for this route: There are optional NSFW scenes: fade to black or mildly explicit, but nothing smutty don't worry.
f) Dialogues are excellently done. Through them, we can see each character's worldview, but also think of the underlying fundamental question which make up the themes of the story: Vengeance or Forgiveness? War or peace? what is the right thing to do after what happened? Do the traitor's reasons justify what he did?
g) Now, while I can understand at the beginning why MC is treated as if they are almost invisible, thanks to their parents, but, it's kind of random the way they are treated later in the story. Even if they are inexperienced on governing, how come the nobles dare to treat their monarch, the last of the royal line, the way they do? And also the diplomatic representative's proposal came out of the blue? What would our ally gain from a second royal marriage between the two countries? I can understand the personal benefit for them, but not of the country itself. Even if a guess-explanation was provided from an MC with high stat on kingdom politics, again it doesn't justify the huge risks the plan itself would pose for the country.
h)As for aether, though explained briefly at the beginning and towards the end by the aether connoisseur,N,there are many questions left unanswered and raised at the same time.

Ending
As for the ending, it left me with mixed feelings, to tell you the truth. I was expecting something more. To see how the monarch fared after what happens. How they rule. Or at least to see the ending of some of the other characters met throughout the story. Alas, my expectations were misplaced. If you are to start playing the game, you should keep in mind that this is the tale of how the last of the royal bloodline of Arcadie succeeds or fails in dealing with the event and protecting their kingdom's future.