I would be interested in playing the AGON games. Which one would you suggest I should begin with?
I've played them in chronological order which is useful when you're new to Agon. The first episode gives you a short overview of what the story will be about; you don't get to do much, it's more of a prologue, introducing you to the mystery of Agon. Episode 2 takes you to Lapland where you need to find the first boardgame and beat its keeper. After that, you move on to Madagascar to find the second boardgame. The episodes become longer as they progress; episode 1 is pretty short while episode 3 takes a while to finish. Also, the puzzles are a lot trickier. Of the first 3 episodes, I think I liked episode 3 best - mainly for the beautiful graphics (that sunset was amazing) and the tricky puzzles.
However, I think you could also start with Lost Sword of Toledo since it doesn't require you to know the background story; it's a new story in itself, the mystery of Agon is being pushed back a little and isn't as predominate as in the predecessors. Also, if you need background, there's Dorothy's table in the main menu to look at; it summarizes the story so far and gives you som background information. The puzzles in Lost Sword of Toledo are a little easier than in episode 3 but still quite a challenge.