A GOOD Generic Repository Pattern

Account.cs

public class Account
{
	Guid Id {get;set;}
	string Name {get;set;}
}

DatabaseRepository.cs

public class DatabaseRepository<T> : IRepository<T>
{
	private IDbConnection _connection;
	
	public DatabaseRepository(IDbConnection connection)
	{ _connection = connection; }

	// Crud is a given
	
	public IEnumerable<T> Find(IFindQuery<T> query)
	{ return query.Find(_connection); }

	public void Execute(IExecuteQuery<T> query)
	{ query.Execute(_connection); }
}

GetAllPlayersInAccountQuery.cs

// This allows you to not have to fudge all your logic into your repository classes.
// So this stops individual Repositories like PlayerRepository : SomeRepository<Player> with custom GetAllPlayers methods

public GetAllPlayersInAccountQuery : IFindQuery<Player>
{
	public Guid AccountId {get; private set;}
	
	public GetAllPlayersInAccountQuery(Guid accountId)
	{ AccountId = accountId; }
	
	public IEnumerable<Player> Find(IDbConnection connection)
	{
		using(var playerQuery = connection.GetCollection<Player>())
		{ return playerQuery.Where(x => x.AccountId == AccountId); }
	}
}

IExecuteQuery.cs

public interface IExecuteQuery<T>
{
	void Execute(IDbConnection connection);
}

IFindQuery.cs

public interface IFindQuery<T>
{
	IEnumerable<T> Find(IDbConnection connection); // this can be abstracted further to reduce IDbConnection
}

IRepository.cs

public interface IRepository<T> // Possibly add K for key
{
	T Get(int id); // you may want to use K as a generic for the key
	void Update(T entity);
	void Save(T entity);
	void Delete(T entity);
	
	IEnumerable<T> Find(IFindQuery<T> query);
	void Execute(IExecuteQuery<T> query);
}

Player.cs

public class Player
{
	Guid AccountId {get;set;}
	Guid Id {get;set;}
	string Name {get;set;}
	PlayerType Type {get;set;}
}

SomeExampleUseCase.cs

public class SomeClass
{
  private IRepository<Player> _playerRepository;
  
  public SomeClass(IRepository<Player> playerRepository)
  {
    _playerRepository = playerRepository; // or if you want to ignore IoC new DatabaseRepository(new SomeConnection());
  }
  
  public void GetPlayers()
  {
    var currentAccount = // Get Account Somehow
    var getAllPlayersInAccountQuery = new GetAllPlayersInAccountQuery(currentAccount.Id);
    return _playerRepository.Find(getAllPlayersInAccountQuery);
  }
}