As 95PGTTech had stated, there isn't much content in your puzzle games, because they all share the same set of instructions, goal and the generic puzzle format. Just because the theme is different, it doesn't make it any more enjoyable then the other submissions.
I just feel that there was much more that you could've added to this game, such as difficulty levels, a (possible) timer and other additions that would make this game look more of a challenge.
I feel like the click boxes in the game are not working properly, or I am just terrible at finding the letters in the game. I see the letters in the images as listed on the bottom left, but literally everything I've clicked is only results in a mistake. And this applies to all 3 images.
This makes quite an interesting twist to the classic tetris-style game, since we have the additional objective of having to connect the pipelines (?) shown in each tile.
It's rare to find difference games like this that are rated highly, so great job developer. The game ran smoothly on my end, the pictures were nice, and the challenges weren't too shabby.
@viguita If you read the instructions, the main goal is to turn all the tiles white to solve the puzzle. Not bad for a concept, but seems fairly easy because all of them is a 1 tiled path. Consider extending the paths to various endpoints or thickening the main path so it adds some form of a challenge for the players.
You added a grid on the main board which makes it somewhat easier for players to fit in the pieces, though I think the other difficulties could've been made better.
It's interesting how the pieces will automatically attach themselves to the (correct) neighbouring pieces, and the BG outline of the owl is neat feat. but it also makes the game quite easy to finish.