I absolutely love a game with ARG elements that contains puzzles and clues that sit both within and outside the context of the game. I did it with my first game, Shellie's Secret. One of the tricks to ARGs though is finding a good path between hinting to the player that they need to use lateral thinking, whilst not tipping off the player enough so that they lose the thrill of discovering something they feel is hidden. You mentioned this is the first part of many, so hope you can explore ideas that bridge those concepts as you build your empire of ARG experiences. Keep at it!