Restructured the project structure back to the way it was, there's no reasonable way to split the modules

src/NadekoBot/Modules/Gambling/BlackJack/Player.cs

@@ -0,0 +1,58 @@
+#nullable disable
+using Nadeko.Econ;
+
+namespace NadekoBot.Modules.Gambling.Common.Blackjack;
+
+public abstract class Player
+{
+    public List<Deck.Card> Cards { get; } = new();
+
+    public int GetHandValue()
+    {
+        var val = GetRawHandValue();
+
+        // while the hand value is greater than 21, for each ace you have in the deck
+        // reduce the value by 10 until it drops below 22
+        // (emulating the fact that ace is either a 1 or a 11)
+        var i = Cards.Count(x => x.Number == 1);
+        while (val > 21 && i-- > 0)
+            val -= 10;
+        return val;
+    }
+
+    public int GetRawHandValue()
+        => Cards.Sum(x => x.Number == 1 ? 11 : x.Number >= 10 ? 10 : x.Number);
+}
+
+public class Dealer : Player
+{
+}
+
+public class User : Player
+{
+    public enum UserState
+    {
+        Waiting,
+        Stand,
+        Bust,
+        Blackjack,
+        Won,
+        Lost
+    }
+
+    public UserState State { get; set; } = UserState.Waiting;
+    public long Bet { get; set; }
+    public IUser DiscordUser { get; }
+
+    public bool Done
+        => State != UserState.Waiting;
+
+    public User(IUser user, long bet)
+    {
+        if (bet <= 0)
+            throw new ArgumentOutOfRangeException(nameof(bet));
+
+        Bet = bet;
+        DiscordUser = user;
+    }
+}