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

src/NadekoBot/_common/Gambling/Betroll/BetrollGame.cs

@@ -0,0 +1,42 @@
+namespace Nadeko.Econ.Gambling;
+
+public sealed class BetrollGame
+{
+    private readonly (int WhenAbove, decimal MultiplyBy)[] _thresholdPairs;
+    private readonly NadekoRandom _rng;
+
+    public BetrollGame(IReadOnlyList<(int WhenAbove, decimal MultiplyBy)> pairs)
+    {
+        _thresholdPairs = pairs.OrderByDescending(x => x.WhenAbove).ToArray();
+        _rng = new();
+    }
+
+    public BetrollResult Roll(decimal amount = 0)
+    {
+        var roll = _rng.Next(1, 101);
+
+        for (var i = 0; i < _thresholdPairs.Length; i++)
+        {
+            ref var pair = ref _thresholdPairs[i];
+
+            if (pair.WhenAbove < roll)
+            {
+                return new()
+                {
+                    Multiplier = pair.MultiplyBy,
+                    Roll = roll,
+                    Threshold = pair.WhenAbove,
+                    Won = amount * pair.MultiplyBy
+                };
+            }
+        }
+
+        return new()
+        {
+            Multiplier = 0,
+            Roll = roll,
+            Threshold = -1,
+            Won = 0,
+        };
+    }
+}