Do you know Sudoku? Or maybe Paint by Numbers (also known as Nonogram)? Sudoku and Nonogram are examples of the many kinds of puzzles also known as "pencil logic puzzles" (for the lack of better terms).
Pencil logic puzzles are puzzles that usually have a grid (so you usually don't need to spare some space just to start solving), and which are typically intended to be filled with pencil or pen (and thus shouldn't be interactive). Moreover, as a logic puzzle, it should have a unique solution, reachable by (deductive) logic alone, and most often these puzzles are culture-neutral in the sense that you don't have to understand any particular culture (except possibly basic math) to solve the puzzles. This rules out things such as knights and knaves (for not having a grid and is also rather culture-heavy), logic grid puzzles (for being culture-heavy), puzzlehunt puzzles (for not being deductive), or puzzle video games (for not being doable with pencil).
So, what are examples of pencil logic puzzles? Sudoku and Nonogram are examples of them, but you might have seen examples such as Battleships, Slitherlink, or maybe recently Fillomino.
There are generally two major types of people indulging in such puzzles. The first one is publishers of these and casual consumers of such; if you've seen Sudoku books in stores, most likely they are made by these publishers. Puzzles in this kind are almost exclusively Sudoku (as the most popular sort), and mostly computer-generated. They sell pretty good, but they are usually of lower quality; after all, computers can generate plenty of puzzles, but can't determine whether they are aesthetically good and stuff.
The second one, which I belong in, is one that enjoys high-quality puzzles, those that are carefully hand-crafted. There aren't so many of us, but if you're looking, you can find a heck lot of them (with apologies to people that I can't think up their blogs fast enough). In fact, there is even a federation complete with its own puzzle and sudoku championships. (Naturally, they are about solving puzzles as fast as possible.)
Now, are you interested in exploring the world of high-class puzzles?
I have collected such puzzles I found in my set here. Feel free to comment here or notify me somehow if you want an inclusion. To be in this set, the puzzle must be a pencil logic puzzle, following the above rules. To be more succinct, puzzles in this set must be: