Just played this and wanted to say how good it was. Many layers and tricky but fair misdirections, like how in puzzle 2 you could find MOBSTER and NOTARY before realizing the theme and the mirroring rule. Very well done!
I just have a bit of feedback about where things didn't quite feel so fair and maybe could be improved.
- In puzzle 10, the the L for LIBRA is supposed to be behind that small blot in the bottom-right corner of the left page, right? But that blot seems too small to actually fit a letter behind it. It's a good idea, to make the player ignore it until realizing it must be covering a letter, but it was so small that I continued to second-guess it even after deducing that it must be the case, so maybe it ought to be just a bit bigger. Similarly, the blot covering the o3 hint for puzzle 5 also doesn't seem like it would actually be big enough to fully cover the text.
- The puzzle titles seemed to be meaningful hints and quite clever, except I'm not sure what puzzle 10's was meant to mean. "Splinter from the Previous" ended up leading me way down the wrong path, thinking that some words were split across gaps (like the two blank spaces in puzzle 3) or even wrapped around from one edge of the layout to the opposite side, similar to how "A Twist" was the introduction to words needing to change direction mid-way. You already broke the normal rules of word searches in a few ways, so I figured that was just another layer of difficulty you intended. Maybe the title is meant to refer to puzzle 2 which was also Zodiac? But I still don't see how "Splinter" makes sense for that, and I think it would be better to avoid the risk of giving people the wrong idea that I got.
- I solved the "AS YOU NOW HAVE WON" message for puzzle 12 on my own, but it was only after coming here that I realized it's meant to be combined with the other messages and have every even message flipped. I didn't bother writing out all the previous messages again, because I thought that was simply for tracking what to search for (as was the case in all previous puzzles), and I figured I could just refer back to where I had already worked them out. I can see how the previously established patterns would have pointed to arranging the messages accordingly on the lines, but the last message (which is the same as the puzzle 12 solution) is shown starting with A, and that's also the direction it's read, which breaks the pattern of messages on the right side needing to be read backwards. So I think it would be good to resolve that discrepancy, and to make it somehow a more explicit part of finishing the puzzle that all the messages need to be combined into one long one. Even the last page implies that finding all 144 searches is the only goal, with nothing else to do beyond that. I'm glad I followed up and checked the comments here, though, because I have a much greater appreciation for this now that I know the full resolution.