new file mode 100644
--- /dev/null
+++ b/pytouhou/utils/random.py
@@ -0,0 +1,36 @@
+"""
+This file provides a pseudo-random number generator identical to the one used in
+Touhou 6: The Embodiment of Scarlet Devil.
+It is the only truly reverse-engineered piece of code of this project,
+as it is needed in order to retain compatibility with replay files produced by
+the offical game code.
+
+It has been reverse engineered from 102h.exe@0x41e780."""
+
+
+#TODO: maybe some post-processing is missing
+
+
+from time import time
+
+class Random(object):
+    def __init__(self, seed=None):
+        if seed is None:
+            seed = int(time.time() % 65536)
+        self.counter = 0
+
+
+    def set_seed(self, seed):
+        self.seed = seed
+        self.counter = 0
+
+
+    def cycle(self):
+        # Named this way because the actual return value may be different.
+        # Further reverse engineering might be needed.
+        x = ((seed ^ 0x9630) - 0x6553) & 0xffff
+        self.seed = (((x & 0x0c000) >> 0xe) + x*4) & 0xffff
+        self.counter += 1
+        self.counter &= 0xffff
+        return self.seed
+