gnome-sudoku: command not found

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On CentOS possible default full paths are:

/usr/bin/gnome-sudoku - from package: gnome-games

You may install the required package with command yum install {package}

Error in other languages:
gnome-sudoku: bevel nie gevind nie
gnome-sudoku: comandă negăsită
gnome-sudoku: comando não encontrado
gnome-sudoku: commande introuvable
gnome-sudoku: command not found
gnome-sudoku: käsku ei ole
gnome-sudoku: không tìm thấy lệnh
gnome-sudoku: komanda nerasta
gnome-sudoku: Kommando nicht gefunden.
gnome-sudoku: kommandot finns inte
gnome-sudoku: komut yok
gnome-sudoku: nie znaleziono polecenia
gnome-sudoku: níor aimsíodh an t-ordú
gnome-sudoku: no se encontró la orden
gnome-sudoku: no s'ha trobat l'ordre
gnome-sudoku: opdracht niet gevonden
gnome-sudoku: parancs nem található
gnome-sudoku: perintah tidak ditemukan
gnome-sudoku: príkaz nenájdený
gnome-sudoku: příkaz nenalezen
gnome-sudoku: команда не найдена
gnome-sudoku: командата не е открита
gnome-sudoku: 命令找不到
gnome-sudoku: コマンドが見つかりません