A look into some of the game design concepts behind “That Castle Game”

Game Economy:
That castle game has a simple economy system where all players have gold, which they gain from income and spend to buy cards from the bank. Players are able to trade/steal other players gold, however most actions in the game either result in a net increase or decrease to the world total gold. Most prices in the game are fixed, however there are 2 events that force the players to bid gold for a desirable effect, and players are free to trade with each other, setting their own prices.

Cost Curves:
Exist in the game, and seem balanced. There are 8 or 9 troop types that a player can buy, costing between 2 and 8 gold, the more the troop costs the more powerful statistics it has, however there isn’t a linear curve to the stats of each troop, nearly every troop has its role in a player’s army relating to its cost and statistics. Some examples:
Goblin Brute, a cheap troop that can soak up damage and be disposed of with little worry.
Knight, a hard hitting troop that deals good damage, but is a meaningful loss should it die.
Elf Ranger, a weak troop that excels in stealth missions and protecting against stealth.
Ogre, a powerful and expensive troop that can deal massive damage and take large amounts of damage for the team that would have killed numerous cheaper troops.
In addition to troops players can buy cards to increase their income, earn victory points or enhance their troops. These cards are similarly priced appropriately for their function and rarity.

Flow theory and progression mechanics:
The starting income of all players total is the minimum starting income of the game, during the course of the game players will, on average, increase in income and be able to hire larger or more elite armies. All troops and heroes also have the potential to level up, allowing them more power in battles, notably the ability to delve deeper into the neutral dungeon.
The challenge in the game is relative to the skills and personalities of the other players, each player able to progress by helping, hurting or ignoring other players at any time. While the game does have some PvE mechanics, how a player overcomes these will result in them surpassing or falling behind the other players.