How would you feel about an adventure game with very little story if you only follow linear path?

How would you feel if you played an adventure game that had a midsize world, lots of NPCs, a fair amount of interactive environmental objects, and most of the back story being told through items you find in the world, the lore that people tell you, and the story bits you find off path?

Imagine a mostly linear experience that kind of funnels you from point A to point B, but it doesn't FORCE you to just travel forward, with plenty of opportunities to leave the forward path and explore a little bit. More and more of the map opens up as you progress, you can find different vehicles, and ultimately you can just explore the whole map as you please, (probably finding, if you do, that the world is a lot larger than the main quest lets on). If you explore, it tells a fair amount of the back story, explains a bit about the world and the characters in it, lets you find items that aren't too important to the game, but deliver more backstory, unless you find them all. If you find all of said item, it unlocks a whole new segment, exploring even more character backstory and world building. A rich world with puzzles, and lots of lore, but if you just plod through following the main story, you are left wondering just WTF is going on?

After the end of the game, a screen comes up showing you all of the achievements you've unlocked, and which achievements remain locked, would that entice you to replay? What could I do to entice a player to play again a little more mindfully if their curiosity is piqued?

Would you feel cheated playing a linear game with little in the way of story if you just follow the rails while ignoring all the signposted clues that you should probably explore a little?

Basically, some achievement collector will feel that. Some of people feel cheated when playing my game because the completion in statistic during end game wasn't 100% when they finished my game, and it isn't even tell a lore. Just about discovering hidden area and accessories.

In your case though, I might also feel cheated, but idk, I never really have much problem or bothered with it as I can easily open up wiki of the game (because most of them has wiki) to read the hidden story about the quest that I didn't unlock during the time I played. Besides I'm not completionist who complete all the achievement. It feels like a labour to complete it all especially when the requirement is too much.

As for replayability, I suggest it's better in gameplay side rather than story side. Maybe you can try a different build to replay the game, because most of people don't like (or simply has no time) replaying the same game with same style over again.

a midsize world - compared to what?
lots of NPCs - this is fine, as long as the NPCs have fun, helpful or interesting dialogue.
a fair amount of interactive environmental objects - more games should have this.
and most of the back story being told through items you find in the world, the lore that people tell you, and the story bits you find off path - optional backstory is always best backstory.

After the end of the game, a screen comes up showing you all of the achievements you've unlocked, and which achievements remain locked, would that entice you to replay? - RPG Maker games don't have much replay value for me, maybe unless your game is short and adds something different to every new playthrough.
What could I do to entice a player to play again a little more mindfully if their curiosity is piqued? - I think that randomising certain elements can help a lot in raising replayability. Things like combat skillsets (just make sure every set is balanced and equally viable), different NPCs in places that say different things, conditional side-quests. But also getting to make choices that matter and change the outcome of scenarios.

Would you feel cheated playing a linear game with little in the way of story if you just follow the rails? - In my opinion, the main story by itself should make enough sense to me if I only read the bare minimums to feel like I understood what was going on, what I was doing and why. Of course, there could still be lots of details that are left out and might make players wondering if they didn't check on it the first time.

Anyway, linear games in RPG Maker work much better than those open world kind of games, because it's much easier to balance around and to test if your game is actually playable (big concern if you're the only one testing your game). Open world RPG Maker games don't work because people making them don't understand what makes open world games work, and even in the rare case that they do, they lack the resources or skill sets to make that kind of game a reality. Therefore, I don't trust any RPG Maker game that labels itself as an open world game.
Linear games are always the superior option for RPG Maker, so don't worry about it too much.

I'm a bit confused about your description, if I understood it right I would feel cheated. (If I understood it wrong then I apologize lol)

On one hand you say that the explorable area brings up optional backstory, lore, puzzles... (which is great, I like that), but on the other hand you say that only following the main path would leave the player feeling "WTF is going on?". Then how come everything you list is optional? If I play a short game, reach the end and find an unfinished or confusing story I would probably feel cheated and I would not replay the game (or not necessarily cheated, more like empty or uninterested). I would feel interested in exploring more if the story/lore was interesting, or if I could get new cutscenes/conversations between the characters. If you need to explore more to find relevant parts of the plot then I don't think it's exactly a linear game, because I feel like those optional paths are not optional anymore.

I don't mind if a game is short or linear, as long as the story or the characters are interesting and I feel like it's complete. Perhaps even leaving some mistery untold, but not necessary feeling like the story is not finished: do you want to know more? then explore more (not replay the whole game). Are you ok with this ending? Then here is this ending (there could be another ending lurking around hint hint).

@UNphiltered_khaos
1) That is what many of us did.We do not create a novel, so we are only tell players little by little. You are doing fine.
2)No matter is open world or close world. You are technically having to hold hands the players and give direction to them. If you are not, we as players would run as chasing a wild goose chase.
3)You want people here to replay your game. You have to a very very good game because many people here can code.
4) I like simple RPG duengon going. However, it is hard to establish moods and narrative in the story aspect.

I don't see anything wrong with having a lot of optional content, and if the optional content can resolve some information the player is told along the main quest but never fully understands it all without going through the optional content, that too is ok to me.

But if the player has absolutely no idea what is going on, on anything, in the main quest unless the play the optional content stuff, then no. I do not see this as being a good idea and I think players would feel cheated for sure.

For that reason I voted "Yes".

Sorry... In my mind now A to B is kinda a visual novel for me sorry ^^ (I know there is way more involved sorry.)

A lot of old adventure games where A->B type games, with no optional paths or dialogue choices.
There's nothing wrong with that, as long as the gameplay follows.

And if you add optional stuff, how could you feel cheated when it's a bonus?

I'm having a hard time following your descriptions, but one thing that sticks out at me is this: What's the point of railroading a player if you're not telling a linear story? I don't think I could really give a fair opinion on the matter without knowing that.

Your idea sounds more like an open world or sandbox game actually. A railroad is only a railroad if you can't leave it.

My understanding of your other question is whether I would feel cheated if you made the main story less interesting than the optional sidequests.
It really depends on how you market the game in the first place. If you market it as a game with awesome story...well...yeah, I would be. Because I came in expecting a nice, well told tale, which could be linear.

But if you market it as an open world/sandbox, then no, I wouldn't, because my expectations coming in is I'm supposed to enjoy the exploration part, and the main story is only tagged on as an extra feature. Just look at say...Starbound. It has a main story, but it's really not the focus of the game.

I have played plenty of games where you found yourself effectively railroaded, but due to the design of the game it never felt that way.

If you allow the story to progress when the players wish it (ie. they can take breaks to look around etc.), rather than forcing stuff down his throat, I don't see why a linear story couldn't be interesting.