Puzzle #3 is Madoku, and it is solved just like Sudoku but using 16 letters. I can't remember the letters but just go through and write down all of the letters listed. Then it is just going through column by column, row by row and then the shapes, some are squares and some are rectangles. I had to start over at least 3 times because I found mistakes and could not track them. It is really just a teaser for the MONSTER
I can't remember what #4 (GC16EFV) is right now but #3
(GC16E7V) took the longest for me.
I am actually sitting here working on the Monster right now. I had to get fancy with different coloured highlighters so I can keep track of different things.
I enjoyed your new puzzles BTW