As can be seen on the jam page description, there's 2 ways it matches the theme "built to scale":
- Firstly, the game itself has been built (designed) to scale (be expanded). The modular system for card effects means more effects could be added, the game itself can be scaled up.
- Secondly, the custom card maker means the player is able to scale the amount of content that is in the game by making more cards.