ksquares: 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/ksquares - from package: kdegames

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

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