Hello, 

i am currently working on a quest system for my game. and i want to make Quest Types Like Gather items type , Kill monsters Type , Go talk to someone mission etc. so my appraoch was like this :

a Class of Quests 

public class Quest
{
 public int ID;
 public string Title;
 public string Description;
 public string CongratulationText;
 public string Summary;
 public Status Status;
 public Goal Goal;
 public Reward Rewards;
 public int QuestGiverNPCID;
public Quest(int iD, string title, string description, string congratulationText, string summary, Status status, Goal goal, Reward rewards)
 {
 this.ID = iD;
 this.Title = title;
 this.Description = description;
 this.CongratulationText = congratulationText;
 this.Summary = summary;
 this.Status = status;
 this.Goal = goal;
 this.Rewards = rewards;
 }
 public Quest()
 {
 this.ID = -1;
 }
}

and the Goal class is : 

public class Goal 
{
 public GoalType type;
 public Gather gather;
 public Kill kill;
 public GoTo goTo;
public Goal(GoalType type, int ID, int AmountRequired)
 {
 this.type = type;
 if (type == QuestEnums.GoalType.Gather)
 {
 gather.itemId = ID;
 gather.AmountRequired = AmountRequired;
 gather.CurrentAmount = 0;
 kill.EnemyID = -1;
 }
 else if (type == QuestEnums.GoalType.Kill)
 {
 kill.EnemyID = ID;
 kill.AmountRequired = AmountRequired;
 kill.CurrentAmount = 0;
 gather.itemId = -1;
 }
 }
 public Goal(GoalType type, int ID)
 {
 if (type == QuestEnums.GoalType.GoTo)
 {
 goTo.NpcGiverID = ID;
 }
 else
 {
 throw new ArgumentException("Wrong type. or number of params does not match the required amount");
 }
 }
}
public struct Kill
{
 public int EnemyID;
 public int AmountRequired;
 public int CurrentAmount;
}
public struct Gather
{
 public int itemId;
 public int AmountRequired;
 public int CurrentAmount;
}
public struct GoTo
{
 public int NpcGiverID;
}

The Goal class defines what kind of quests its going to be . for example it s a gather mission : i cant construct a new goal with type gather , item that is going to be picked and required amount. so this approach works. but i m not satisfied and im not convinced that this is a good approach it feels noobish and hacked not a solid design. so if it s possible to hear some good approaches and technics to achieve Goal quests :c and thank you for your time