It is a decent game, but it has a few design flaws that ruin it.
The graphics and levels of the riddles are that of maybe a 3-5 year old. Simple match the pictures, spell a basic first word "hello" and so on. As that, it would be great!
However, your mathematical skills use the term of Bedmas which is a term learned in higher elementary. So your player temporarily dismisses that rule in order to match the math level of the target player (a 5 year old) although the multiplications in there bumps it up to a 3-4th grader, so it still works as a kids game, although not one skilled enough to know Bedmas. The math is read by the player in left to right method resulting in:
What /4=3... well 3*12 equals 4, So 12/4=3 12-4=8 so the first answer is 8!
And so on. They waste too much time popping their mind out of your game for a bit to figure out that the answer is 2545.
You created a wold before the maths theory that you have used existed, and the point of a game is to keep your player in that perimeter of logic. So any jump in logic like that (being rare) is illogical, and defeats this cornerstone of gaming.
Another flaw that exists is the "Read the Answer before you solve it" rule. Sure, that keeps the cheats away, but when I grabbed the crumpled paper out of the garbage, I shouldn't have to click an extra time to take it out of view mode and into my inventory. Then, when I placed it next to the light, that should have been the trigger to unlock the puzzle to be solved, rather than having to bring a page with me I need not look at. Same thing with the butterfly in the flowers. When I put it there, I can clearly see the code. No need to click further... I think you get my drift.
To summaries, Your game has aspects of logic pertaining to at least three target players. However, that means that the logic peramiters of the games clash with each other and people playing the game will have to break out of the game and come back into it with a whole new mindset. For a game with the looks and the length that it is, and difficulty level of finding the clues, not needing to take a second look and the simpleness of a repeated 3 pattern code in which the middle one is always the default, You haven't done anything to create any invested interest enough for a player to play through it.
I didn't need the walkthough in itself. I got it all, however, the clicking on the clues that one extra time did make me wonder why the clues weren't working. Focus on who you want playing the game. Everyone is not an option... look at age groups, genders (when it comes to little children, they are divided) the interests and skills of those targets and focus on them. The reviewers like myself will be able to read that and follow along putting themselves in that mindset and you will have a success.
I wish you the best of luck in the future.