Tabletop Game Design for Video Game Designers uses Kingdom Rush to illustrate how one might go about creating a “comparable basis.” Establishing a comparable basis is a useful technique for determining an initial design for a game’s various numerical data (such as what each type of tower costs in Kingdom Rush).
Here is a “tower pricing” spreadsheet that I created to work through the comparable basis I present in the book. It should be noted, that the spreadsheet is my own creation and not necessarily how Kingdom Rush‘s designers went about pricing the game’s towers. Even so, it is a useful example of an important designing technique.
See also: “Monster Hunter.”