I've been working this well before the jam, but decided to finish it up when I saw this jam published. This ruleset hits Nightmare Mode in all four areas:

• It doesn't use any tables, ordered lists, or unordered lists
• There is no expository or narrative writing
• This is an all-new ruleset that does not rely on any other supplement or SRD
• It is less than 1,000 words (960 total)