itch.io

Other than the number ticket or the bucket which would probably have a purpose in the full release, every other item you mention serves a purpose as another route/path.

The candle is part of a route as a way to skip finding the keys and doing that dark forest area and the valves is way to drain the water instead of having to solve the elevator problem. There are also several other item that have uses too, the only exception are the ticket, the bucket, and the fish.
Assuming that the fireplace puzzle is difficult for you, I doubt that you will understand how to do the potion route and most likely missed the majority of characters in the forest.

Plus, other than the several chases in the game, I don't see any of the mini-games being that difficult and that it's probably the device you're playing on is slow or that it's just you.
Either way, if this is considered to be a hard game for you, then you haven't played many horror RPG games.

The game isn't so hard, you just need to understand things and use your brain, the objectives are pretty clear if you use your brain, Sai is an amazing character, hell, maybe he's clingy, but the fact that he didn't sacrifice us was a good thing, removing him would pretty much destroy the game, as he was there to help the mc that she could change, and him feeling comfortable with her was something new for her, as only her brother had felt that way with her. 

The minigames are fun, they might be complicated, but, that's what makes them so fun, you can always skip them if you are not good enough to beat them. Potato chips are used on so many ways, the bucket is also useful, valves are pretty important too. If it's too hard for you, you can always just quit or follow a guide, I've seen good guides online.