diff --git a/checkgamebook.py b/checkgamebook.py
new file mode 100755
index 0000000..3a517e3
--- /dev/null
+++ b/checkgamebook.py
@@ -0,0 +1,48 @@
+#!/usr/bin/env python2
+
+"""
+Copyright (c) 2014, Pelle Nilsson
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+Redistributions of source code must retain the above copyright
+notice, this list of conditions and the following disclaimer.
+
+Redistributions in binary form must reproduce the above copyright
+notice, this list of conditions and the following disclaimer in
+the documentation and/or other materials provided with the distribution.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+"""
+
+import os
+import os.path
+import sys
+import json
+
+USAGE = "usage: %prog [options] inputfile(s)... outputfile"
+
+def check_gamebook(inputfilename):
+    book = json.load(open(inputfilename))
+
+if __name__ == '__main__':
+    import argparse
+    ap = argparse.ArgumentParser(
+        formatter_class=argparse.RawDescriptionHelpFormatter)
+    ap.add_argument('inputfile', metavar='debugfile',
+                    help='input gamebook debug file (eg test.debug)')
+    args = ap.parse_args()
+    check_gamebook(args.inputfile)
diff --git a/todo.org b/todo.org
index be8accd..a7680ba 100644
--- a/todo.org
+++ b/todo.org
@@ -1,4 +1,4 @@
-* TODO [61/83] [73%]
+* TODO [62/92] [67%]
 ** DONE Debug output
 ** DONE DOT output
 ** DONE LaTeX output
@@ -77,6 +77,10 @@
   test those from nodejs?
 ** DONE Make debug output more useful with a stricter format easy to parse.
    Will be taken care of when implementing JSON output.
+** DONE checkgamebook.py script, parse debug file JSON
+   CLOSED: [2014-09-23 Tue 21:52]
+** TODO checkgamebook.py build internal section graph
+** TODO checkgamebook.py find unreachable sections
 ** TODO JavaScript improved design/code for what links to enable
    Many strange things can happen when clicking one link changes something
    that should now enable or disable some link. Instead of the current
@@ -133,12 +137,12 @@
 ** TODO Somewhat user-friendly js error messages and always fail early
 ** TODO More formatting possibilities in sections
   Look at existing gamebooks to get ideas to add to this todo list.
-** TODO Document Gamebook format
-  - Basic gamebook (static, nothing about magic needed for dynamic; tutorial)
-  - Advanced (more complex layout options, but still static)
-  - Dynamic (markup needed to make playable (HTML) version)
-  - Standard output formats reference
-  - Customization (make new output formats or override existing)
+** TODO Document Gamebook format Basic gamebook (static, nothing about magic needed for dynamic)
+** TODO Document Gamebook format Advanced (more complex layout options, but still static)
+** TODO Document Gamebook format Dynamic (markup needed to make playable (HTML) version)
+** TODO Document Gamebook format Standard output formats reference
+** TODO Document Gamebook format Customization (make new output formats or override existing)
+** TODO Reference documentation (all default template tags)
 ** TODO Make it possible for a modifier tag to refer to any other tag
 Currently a modifier (eg cost) always applies to tag on its left or right,
 and it can be a bit confusing to remember what direction, or awkward to
@@ -173,4 +177,5 @@ listed even if it is not tagged.
     differently from the normal include/exclude tags unfortunately.
    Allow multiple sections with the same name, only use one that matches,
     or treat as any other missing section otherwise.
-** TODO Dummy and fake sections (handle properly when verifying)
+** TODO checkgamebook.py ignore dummy and fake sections
+** TODO checkgamebook.py trace items to find sections they are needed but can not have been found