diff --git a/README.md b/README.md
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--- a/README.md
+++ b/README.md
@@ -1 +1,31 @@
-# er-patcher
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+# Elden Ring Proton Patcher
+
+
+A tool aimed at enhancing the experience when playing the game on linux through proton.
+
+## Features
+
+- set custom frame time limits (e.g. 30, 90, 165, ...)
+- disable black borders when using resolutions with an aspect ratio other than 16:9 (e.g. ultrawide).
+- vigniette removal
+
+## Usage
+
+1. Copy the file `er-patcher` to the game directory.
+2. In steam, set the game launch options to `./er-patcher ARGS -- %command%` where ARGS is replaced with a combination of
+  - `-r RATE` or `--rate RATE` for setting a custom framerate cap (default: 60)
+  - `-u` or `--ultrawide` for removing black bars
+  - `-v` or `--vigniette` for removing the vigniette overlay
+  - Example: `./er-patcher --rate 30 -uv -- %command%`
+  - Example with mangohud and wine fullscreen fsr: `./er-patcher --rate 30 -ucv -- env WINE_FULLSCREEN_FSR=1 MANGOHUD=1 MANGOHUD_CONFIG=histogram %command%`
+3. Launch the game through steam. `er-patcher` automatically launches a patched version of `eldenring.exe` with EAC disabled.
+
+### Windows
+
+It should work on windows, just as well. The only difference is, that you need to run the script via your python 3 installation. Depending on the version of python 3 you have installed you would need a slightly different path than shown in the following example.
+
+Example: `C:\Program Files\Python36\python.exe er-patcher --rate 165 -uv -- %command%`
+
+## How it works
+
+When the game is launched through steam, the tool creates a patched version of `eldenring.exe` called `eldenring.patched.exe` while leaving the original intact. The tool then modifies the steam launch command by replacing the string `start_protected_game.exe` with `eldenring.patched.exe` so that the patched exe is always run without EAC. After the game is closed, `eldenring.patched.exe` is deleted.
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diff --git a/er-patcher b/er-patcher
new file mode 100755
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+++ b/er-patcher
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+#!/usr/bin/env python3
+
+
+import os
+import sys
+import subprocess
+import argparse
+from pathlib import Path
+import struct
+import code
+
+
+if __name__ == "__main__":
+
+    patcher_args = sys.argv[1:sys.argv.index("--")]
+    
+    parser = argparse.ArgumentParser(description="Patch Elden Ring executable and launch it without EAC.")
+    parser.add_argument("-r", "--rate", type=int, default=60, help="Modify the frame rate limit (e.g. 30, 120, 165 or whatever).")
+    parser.add_argument("-u", "--ultrawide", action=argparse.BooleanOptionalAction, help="Removes black bars when using a resolution with an aspect ratio other than 16:9.")
+    parser.add_argument("-v", "--disable-vigniette", action=argparse.BooleanOptionalAction, help="Disables the vigniette overlay.")
+    patch = parser.parse_args(patcher_args)
+
+    with open(Path("eldenring.exe"), "rb") as f:
+        exe = f.read()
+    exe_hex = exe.hex()
+
+    if patch.rate != 60 and patch.rate > 0:
+        exe_hex = exe_hex.replace(
+            "c743208988883ceb43897318ebca897318",
+            "c743208988883ceb43897318ebca897318".replace(
+                "8988883c", struct.pack('<f', 1 / patch.rate).hex()
+            )
+        )
+
+    if patch.ultrawide:
+        exe_hex = exe_hex.replace(
+            "8b0185c07442448b5904",
+            "8b0185c0eb42448b5904"
+        )
+
+    if patch.disable_vigniette:
+        exe_hex = exe_hex.replace(
+            "f30f590514a76e01f3440f5cc8f3450f5ecb",
+            "f30f590524b56e01f3440f5cc8f3450f5ecb"
+        )
+
+    patched_exe = bytes.fromhex(exe_hex)
+    patched_exe_path = Path("eldenring.patched.exe")
+    with open(patched_exe_path, "wb") as f:
+        f.write(patched_exe)
+
+    # start patched exe directly to avoid EAC
+    steam_cmd = sys.argv[1 + sys.argv.index("--"):]
+    steam_cmd[-1] = steam_cmd[-1].replace("start_protected_game", "eldenring.patched")
+    subprocess.run(steam_cmd)
+
+    os.remove(patched_exe_path)
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