Hi. These are my own walkthrough notes when reading through this VN,
and I figured it should be helpful for other people too.

If I have made a mistake somewhere, do tell me in the comments section, I'll make the adjustments.

I have only started this VN 3 times, so a lot of the routes may share similar beginnings.

• 1st start = Fin ~Before it began~
  
• 2nd start = Bad End, Melody / Scherza / Lyria routes
  
• 3rd start = Harem End

10 of the 11 achievements are gained just from reading the VN,
which for the sake of being neat and tidy,
I will insert them within the routes in the form of spoilers.

For the 11th achievement, I've seen some forum threads with people saying they had problems with Start The Game achievement. Some solutions are:

* If you tried the demo version first, then bought the VN, don't load the save, just Start New Game.

* Alternatively if you have the demo but haven't bought Starlight Vega yet,

• delete the local content of Starlight Vega demo from your Steam Library
  
• also go to your Steam Account Details
  
• View Licences and product key activation
  
• look for the the Starlight Vega demo record, and manually remove it
  
• then buy the VN and Start New Game.

* There shouldn't be any problem with that achievement if you just immediately bought and started this VN without touching the demo version. (same case for Kickstarter backers who received a Steam key)

The easiest ending to get (LOL).

• Don't touch it.
  
• No, let's leave.
  
• Fin ~Before it began~

• Pick up the gem.
  
• Be rude.
  
• Agree.
  
• Nevermind...
  
• Suggest handheld with limited battery life.
  
• Alright... I guess you can stay.
  
• Go meet Melody.
  
• Check the weird things on the shelves.
  
• ACHIEVEMENT: Moonlight
  
• Hell no.
  
• ACHIEVEMENT: Melody...in a dress ?
  
• Fin ~Forgotten~
  
• ACHIEVEMENT: Bad End

• Pick up the gem.
  
• Be rude.
  
• Agree.
  
• Nevermind...
  
• Suggest handheld with limited battery life.
  
• Alright... I guess you can stay.
  
• Go meet Melody.
  
• Check the weird things on the shelves.
  
• Might as well...
  
• ACHIEVEMENT: Sweet Love
  
• I'm sorry.
  
• I love you, too.
  
• Fin ~Homecoming~

• Pick up the gem.
  
• Be rude.
  
• Agree.
  
• Nevermind...
  
• Suggest handheld with limited battery life.
  
• Alright... I guess you can stay.
  
• Go meet Melody.
  
• I'd like to know more about these weird dreams I've been having.
  
• What if I said neither...?
  
• Hell no.
  
• Attempt flattery.
  
• Okay, I'll do it.
  
• It's a bit plain-looking, isn't it?
  
• How old are you?
  
• Thank you. I'll put it in my cell.
  
• Try to escape.
  
• It's better to return home.
  
• Fin ~Unfinished Remorse~

If you have been following my notes so far,
there is only one choice difference compared to Scherza route Bad End,
which is the last choice.

• Pick up the gem.
  
• Be rude.
  
• Agree.
  
• Nevermind...
  
• Suggest handheld with limited battery life.
  
• Alright... I guess you can stay.
  
• Go meet Melody.
  
• I'd like to know more about these weird dreams I've been having.
  
• What if I said neither...?
  
• Hell no.
  
• Attempt flattery.
  
• Okay, I'll do it.
  
• It's a bit plain-looking, isn't it?
  
• How old are you?
  
• Thank you. I'll put it in my cell.
  
• Try to escape.
  
• Follow after her.
  
• ACHIEVEMENT: Let your guard down.
  
• ACHIEVEMENT: Kiss the queen.
  
• Fin ~Break of Dawn~

The game actually lists this route as Fin ~Forgotten~,
but since there is another route with the exact same name,
I'll just self-designate it as Fin ~Forgotten 2~.

• Pick up the gem.
  
• Be rude.
  
• Agree.
  
• Nevermind...
  
• Suggest handheld with limited battery life.
  
• Alright... I guess you can stay.
  
• Spend lunch with Lyria.
  
• I guess I wouldn't mind...
  
• Hell no.
  
• Let's not diverge from the plot too much.
  
• ACHIEVEMENT: This is not my idea of romance !
  
• ACHIEVEMENT: What is she hiding ?
  
• Earlier, we saw your father...
  
• Yes...
  
• ACHIEVEMENT: NTR
  
• Fin ~Forgotten~

If you have been following my notes so far,
there is only one choice difference compared to Lyria route Bad End,
which is the last choice.

• Pick up the gem.
  
• Be rude.
  
• Agree.
  
• Nevermind...
  
• Suggest handheld with limited battery life.
  
• Alright... I guess you can stay.
  
• Spend lunch with Lyria.
  
• I guess I wouldn't mind...
  
• Hell no.
  
• Let's not diverge from the plot too much.
  
• Earlier, we saw your father...
  
• Refuse advances.
  
• Fin ~The Girl from Vega~

• Good End for Melody,
  
• Good End for Scherza
  
• Good End for Lyria.

• Pick up the gem.
  
• Tell name.
  
• I think she's alright.
  
• Did you have anything you wanted to know ?
  
• Suggest fashion magazines.
  
• Alright... I guess you can stay.
  
• Go meet Melody.
  
• I'd like to know more about these weird dreams I've been having.
  
• I really like them both.
  
• Might as well.
  
• Ask to go home.
  
• Differences between humans and demons.
  
• ACHIEVEMENT: Holy Harem
  
• Fin ~Harem Ending~

Yes, I've checked, the CG names Playtime, and Acting, are on Page 2 & also on Page 3.


There are 2 missing CGs from the Gallery:

• one of them is definitely a Harem Ending CG (which is not in the Gallery due to a bug)
  
• not so sure about 2nd one, will update on that later.