mahjongg: 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/mahjongg - from package: gnome-games-extra

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

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