Sorry for the long response, XD I’ll split it up to make it easier.
Overall: Yes, I certainly want them to have an impact.
In short: Yes!
The big choices certainly do, e.g. Marrying Arthur/Elaine or not changes his/her reactions and expectations of you throughout. Not being married allows you to have relationships without fear of having an affair on a monarch and not being officially allied with Camelot. Being married allows you to have an affair and I plan on implementing a light barony management aspect to the married route.
Telling everyone if your father will betray Camelot or not is also another big choice that will have consequences either way. ‘Betraying’ Camelot or lying about your father’s intentions will result in the war branch throughout Chapter 2 and the effects of the war going ahead will change how badly Camelot is affected throughout the later chapters. Telling the truth results in the peace path and will obviously result in less damage to Camelot. It may also open up more subtle ways of betraying Camelot in the future if you didn’t take the most obvious choice in that chapter.
In short: They change the text and add unique conversations.
Being a vegetarian/drinking/right-handed, are only flavour choices really and might bring in a few unique dialogues with certain characters. There are a couple rarer choices you can make that get remembered just for fun: Mentioning your dislike of violence to A/E, telling Kay you hate fish and later eating fish in front of him, the scars you can obtain etc.
A lot of the choices are to allow the player to react and respond in the way they like, and/or avoid spending time with characters they might not be that interested in talking to. How you speak to characters can change their relationship to you, and your relationship to characters changes their general responses to you if you try to do certain things with them or approach certain topics.
In short: Yes, they change their opinions of you and control how much you can influence them.
You need a high enough relationship to access certain scenes, there’s a negotiation-talk scene that can only be done if Kay likes you enough, for example, in the peace branch.
If you marry A/E but never spend any time with them or actively are mean, they will not have a romantic relationship with you, even if you want it. You require a positive relation for the option to not be platonic. You will naturally need high enough relationships with the characters to enter into relationships in general. I plan for relationships to be capable of ending if you’re not fulfilling that character’s individual needs. (They won’t just break up with you out of nowhere, I will include serious talks where a RO’s needs will be made clear when you’re lacking.)
In Chapter 3, which I’m writing now, there’s a fairly important relationship check that could change how a major character views another character for the rest of the game. If you plan on betraying Camelot, having allies will be very important and will impact the endings ideally.
Hmm, I recently took part in the Halloween game jam that I posted above, but other that, this is the first piece of interactive fiction I have ever shared publicly. And yes I can read lol