So is the TSW5 starter pack A demo? A limited time trial? A timed test demo? A free basic core training area game? Is it playable even if you don't buy any other full routes until later.
It is meant as a means of allowing players of TSW2, TSW3, or TSW4 to upgrade to TSW5 without the routes. This way, you don't have to pay to get bugfixes for compatible content if you aren't interested in the core routes. If you claim it before October 17th, you keep it forever. Your compatible content comes with you. You can buy more routes afterwards if you wish. It comes with the Training Centre, so even new players can get it.