Install requirements:
Ruby / Sass
You can install Ruby through the apt package manager, rbenv, or rvm. Install Sass through your Terminal or Command Prompt.
$ gem install sass scss-lint
$ export PATH="~/.gem/ruby/2.1.0/bin:$PATH"
$ sass -v // should return Sass 3.3.8 (Maptastic Maple)
Complete process for all OS at: http://sass-lang.com/install
Node + Bower + Gulp
$ sudo npm install -g gulp
$ sudo npm install -g bower
$ npm install
$ bower install
$ gulp
And go in your browser to: http://localhost:9001/
If you have any doubts or any questions related to taiga's software, you can use this Mailing List.