\documentclass{article}

\usepackage{czech}
\usepackage[utf8]{inputenc}
\usepackage{sudoku}

\author{Radi}
\title{Příklad jednoduchého sudoku}

\begin{document}

\maketitle

\begin{sudoku}
|2|5| | |3| |9| |1|.
| |1| | | |4| | | |.
|4| |7| | | |2| |8|.
| | |5|2| | | | | |.
| | | | |9|8|1| | |.
| |4| | | |3| | | |.
| | | |3|6| | |7|2|.
| |7| | | | | | |3|.
|9| |3| | | |6| |4|.
\end{sudoku}

\end{document}