I just bought and started a new game: Lake Ridden.
It is a mystery game with lots of puzzles, logical puzzles. You have to look closely and think logical than you can solve the puzzles.
I like it a lot, Marinus_Louis is also playing this game. He is already further ahead and he is also enjoying this game.
It is a adventure, mystery and puzzle game, if you like the Myst games and games like that, then you should look at this game.
You can buy the game at GOG and Steam.