The definition of “Currency” in Collins is “2. general acceptance or circulation; prevalence”. Currency in the game means the measurement and representative to all different elements in the game. Currency which is defined by the designers can help a lot on prototyping the game system.
In this phase, one of the important work is to create contents such as skills, weapons, and enemies. With a currency, creating similar elements with variations are much easier. Moreover, having a currency makes the whole system more clear which facilitate divergent thoughts.
Case 1 – Hearthstone
The critical principle behind currency is the relationship between the currency and any other elements. There is an obvious currency in Hearthstone, the mana crystal.
- 1 Extra Card = 1 Mana;
- 1 Attack / Health = 0.5 Mana;
- Silent = 1 Mana; Taunt = 0.5 Mana;
- 1 Hit Point = 0.33 Mana;
- Hero Special Card = 1 Mana;
- 1 instant damage = 1 Mana.
Windfury, Charge and Divine Shield are more complex. They highly depend on the attack or the health of the minion. Based on this, creating various and balanced cards are much more fluent. At the early stage of Hearthstone, most of the cards are highly restricted by this currency. For instance, the Bloodfen Raptor and River Crocolisk are 2 Mana cost, so the summed attribute are 2*2 + 1 = 5 (All minions have a base of 1 attribute). Later, with more and more new features introduced into the Hearthstone, mana as a currency has more and more little sense of presence. Balancing different cards depends more on testing and statistics.
Advanced feature – Invisibility
Start with a currency and abandon it later. It is a very popular phenomenon in game design. The reason behind it is that currency has double-edges. In the prototype phase, currency is a good assistant, with its help designers can create a bunch of balanced contents effectively. However, when the prototype grows up, players expect more new things in the experience. Currency makes them think in a same and simple frame which impairs the feeling of having new things. So in refine phase, one of the important feature of the currency is invisibility.
Case 2 – Heroes of Might & Magic 3
Currency is useful in early phase of developing a game. Then it should be hided in the later phase.