You did a really, really good job with this game. The characters are quite nicely done, though there's still room for improvement (sprite-wise cause some of the positions looked a tad awkward). But the overall development and different personalities you gave them are good and mostly different than some in the other VNs I've played.
The BGs are quite nice, though they could have probably be more realistic because to me, I think, a visual novel should be able to enchant people and draw them into its world. Be the character, live as the character, and so on forth. You're quite close, cause I could almost feel like I was Mina while playing the game, so kudos to you for that! Just a bit more, and I think you'd have it.
Music-wise, it's very fitting. The sound effects
The plot is especially very well done. It's not your typical cliché plot (which is impressive). You made the heroine vulnerable, but still powerful (literally and figuratively) in her own way. And the twists you gave to each path were amazingly done.
I'm very picky about plots and storylines (almost to the point of extreme) because being a writer myself,
And the cut-scenes? Love them.
My thoughts about characters are below (in no specific order). Used the spoiler tag just in case....
Well, I don't want to take up too much space, so I'll make it as short as possible. Personally, I think Caius is like a demonic protagonist (reminds me of Hiruma from Eyeshield 21 a bit). He's like a mixture of Sai and Hidan from Naruto. A sadist with a penchant for violence, yet in strangely vulnerable and uneducated in other aspects. (Poor guy.) The festival scene was so cute. Ahem. His endings (both) were nicely done ^_^
Runne - Life Path
On one hand, his laid-back/serious attitude is engaging. On the other hand, sometimes I feel like face-palming or just sighing at his overprotective-ness and stubbornness. Though, once you get under his skin, he's rather quite sweet. That scene nearing the end when they touched hands was so worth it. And the True Ending was just...
Varian - Fire Path
I swear, he's like one of the most complicated characters ever. But.....interesting. A very different take on the average stereotype, so kudos for that. Grim, determined - but lost - and extremely righteous. When Varian was sitting on the other side of the door and Mina on the other - that was just heart-wrenching. A workaholic, but...Mina brings the best outta him so that's solved >.>
Aurelius - Wind/Air Path
Egoistical womanizer *cough* with charisma and an intriguing background. His scenes are quite endearing in a way - loved the snowball scene hehe. Personality-wise? His ego's large (thank goodness for Cascade and Mina *cough*), doesn't really fully listen to people but he makes it up by being charming and sweet to boot as well as the determination to find out the truth before judging people unlike certain characters.
I really, really didn't expect it to be you-know-who. And no, I'm not talking about Voldemort. Really. This came as a surprise to me. But the scenes and all, and the way Mina's thoughts went and everything else fitted nicely. Everything made sense. I sympathized with the guy >.> His ending is very well done. Loved the interactions and the background story.
I look forward to your future projects