Part 1 of 2
Starting up the demo, first thing's first: The "of" is placed such that your eye isn't drawn to it but in fact AWAY from it, since the bottom line of "valley" matches up pretty well with the flourish of the bottom of the A in "Ashe", *and* the word "of" is also a few font sizes smaller; English-speaking people default to read from left to right, top to bottom, which doesn't help it here. There's also a lot of blank space; I'd increase the dimensions to be at least twice the size it is proportionally, and increase the fontsize of and reposition the "of" to be between "The Valley" and "Ashe", moving "The Valley" to the left to be in front of more of the background art as well.
Second issue is the audio starts off EXTREMELY LOUD, and there's no Title Menu options where you can alter the sound volume. RPG Maker games by default always jack the sounds up to 100% and they come across very loud on most setups that can be used to watch Youtube at 10% sound mixer, 50% speakers, and 10% Youtube volume, to where even adjusting them to 10% output in the sound mixer with speakers at 50% has them still being too loud.
Starting the game proper, beautiful background music (but too loud, as above), but the typefont used has a few letters with small blobs that jut out and draw the eye to them, like on the bottom of the "e", and the shape of the "g"'s tail is too sharp, as well; additionally, the font isn't aligned properly horizontally, such that some letters hang below others, and it actually disturbs reading flow, and, frankly, looks a bit amateurish. The font style otherwise is pretty good, like a combination of cursive and blocktype fonts to evoke fantastical elements. The clacking sound when type scrolls onto the screen also is annoying in general, as well; it's too harsh a note to repeat as rapidly as the text scrolls onto the screen. Maybe something a little softer?
First image appeared, and the art is gorgeous. The story is interesting, but the way it's written needs work; At first you write that "Navi escapes with his life. The Horde followed" and continued on to talk about the humans for a bit, but then you suddenly mention that "Not all of the Horde followed Navi" without indicating so beforehand, nor with a, "However,"; and "Slowly, the monster attacks increase" without really indicating that attacks from the monsters were ongoing during this period, either.
Into the first scene of the in-game artwork, and it's gorgeous. A++ effort, here. Love the character design; The kid looks way too old in his bust shot compared to his little shrimpy model, though; or is it that you're still working on transitioning from the chibi models to the larger ones? Story pacing issues still here, though. The red-head twintail says "We'll make the monsters pay!" before saying "What happened?", for example; the question should have come first, followed by the explanation, then her exclamation. The 'cutscene' with the father shows him alone in the mines when you'd just said there were "so. many. undead."; maybe put a bunch of the enemy model you used to attack him and have the son kill crowding the mines behind him, so it actually visually represents that. In that scene as well, the kid says "come on, lets go home, dad." but in the next few lines when it transitions back, he talks about how his mum had already died and "now with my father dead..." but nothing there implied his father dying, only that he was attacked and left badly wounded; show us that, maybe just a short scene transition to him standing at a pair of graves sobbing, with one old (grass in front) and one new (recently disturbed earth)? Pacing issues in the story are the biggest issue I'm seeing all around, here. The core of what the story is, is decent, but just the how of the telling is the problem, if you get what I'm saying.
Second scene, Valen just suddenly in the forest immediately when he just said he's going to it. A: if the Elven Forest is a place players can go to, show Valen travelling to it on the map, perhaps? B: He shouldn't just "be there" in the middle of the forest in front of the elf as soon as the scene begins, regardless. If there was another scene with other characters before this, temporal pacing could be held, wherein we see that scene and the time passing seeing that can be used to infer travel time; Same with if he was another character entirely, because we haven't tagged them as a character of interest and their direct movements as important to the story until that point.
Part 2 of 2
At the end of that scene, when character control is given, first thing I do is check the menu, and it is really solidly built; reminds me of Tales of Destiny in its style. Finally access to the options menu! This said, with the Equip screen showing the status of the character and their equipment, what, exactly, is the point of the Status screen? In Final Fantasy VI, which did this, there was a plethora of information available on secondary statistics and other notable things that only showed on the Status screen, so it had a purpose there for number crunchers; I can't see a reason for it here separate from the Equip screen, though.
First random battle starts up, and immediately, there's a bunch of things I notice that are wrong. The in-fight sprite, if you're going to have it animated to attack, should not just slide across the ground; archer characters also don't exactly need to move to fire their bow, either. Secondly, whenever Valen gets hit, and during the end of battle sequence when he's victorious, he briefly morphs to this... pixel art samurai version of himself? It looks quite a bit better than the hand-drawn art, probably because of the proportions and angle, as it's shown straight from the side instead of a weird isometric view that doesn't mesh with enemy sprites, battle screen layout, or battle animations; he also doesn't have a foot levitating off his shadow, either. Third, it seems all enemies operate off the same ATB timer speed, and it's always faster than you are; I can understand hornets being fast, but slimes? Plus, it's locked into an active ATB style without an option for a wait ATB style, which many of us RPG veterans prefer. Fourth, Valen's Firebolt skill says in the description that Sylvyth enchants his Focused Shot with fire... so why is it listed as costing *Valen* MP, instead of TP? Fifth At battle end, the victory screen force-transitions into the end-battle screen; leave this to the player to do, if possible, and try combining the battle spoils screen with the previous one; a whole screen for 18g is pretty meh.
Related note: If this is supposed to be the Elven Forest where it's one of the last few safe places from monsters, why are monsters attacking in it? I get the hornets (but not that hornets have life steal), but aren't slimes generally considered to be monsters themselves? Would think that any combat here would be animals-only because of that.
Out of combat, wandering around... and my head is clipping behind the tree's roots spritework. Click my mouse by accident, and there's an annoyingly fast flashing white square that Valen's now wandering to?... No, wait, he only took a few steps towards then randomly stopped. And he can't exit maps with it, either. Please either fully integrate mouse controls (in battles too; a click anywhere on screen should be the same as pressing "Z" to activate the currently highlighted item, instead of having to directly click on it) or disable them entirely. Even if it's an options menu toggle.
In "Ashe Town" (Shouldn't that be "Village of Ashe" going by the size?), first thing's first: Doorways are black voids into nothingness that are tile-edge-matched to the bottom-adjacent tile. This is really offputting becuse it's a flat, 2D plane in an isometric view. It's also completely un-edged so it looks like the tile textures of the surrounding tiles just abruptly stop; the stone border at the foot of the houses, as well as the plank siding of the buildings themselves. General Store lacks any identification like a sign, statue, or distinctive build style. When transitioning between screens, you place the player's model in the same space as the transition; the player should actually be one step beyond the transition tile in the direction they entered the transition point from (enter north, move one tile north on next screen, etc) to facilitate entering a building not intended and being able to leave immediately, or, upon leaving a building, and realizing you forgot something, being able to immediately re-enter. Also, to prevent being placed in the doorway tile and unable to immediately move left/right before you exit that tile.
I'm going to end it here; it's a great effort, especially for a one-man team, but there's a lot of problems and rough edges to it that I really hope to see get cleaned up in the future.