You do not begin play with one set of worker runes and plans for a particular race; you start with basic runes and a few plans for all six races. There’s no gradual build up, getting to know each race individually and systematically, presumably because anyone who plays the game will have already finished TOoD at least once, so knows their way around the territory, as it were. In the original, of course, you started play with human units, and on subsequent levels advanced through elves, dwarves, orcs, trolls and dark elves, each race becoming progressively tougher as the enemies became stronger too. In BoW, enemies are pretty tough from the start.