This instruction can be used for Ubuntu, Debian, Mint, SteamOS and other debian based distros.

Install this file: manaplus-addrepo_1.3_all.deb

Run in terminal:

sudo aptitude update
sudo aptitude install manaplus

or

sudo apt-get update
sudo apt-get install manaplus

or select and install in synaptic package manaplus

See also: Ubuntu & Debian repository, screenshots

Debian, Ubuntu