I'm working on my Open RPG system in an A6 format with 0.5cm borders. I'm visualizing this as a small compact booklet of about 300pages, but more importantly a PDF for your smart phone. No Big tables, only tables that would fit a A6, and the rest are formulas where there will be mnemonic notes.
My biggest strength is Logistics, I'm using the Small Wars Manual and a basis for all the animal performance stats. There will be a lot of Animal stats and the supporting equipment like Carts, Wagons, and Chariots.
There will be Household, which involves all the personnel typical of a household and an adventuring staff. I place into household all the supporting personages like the scholars, guards, heralds, agents, stewards, etc... I'll be using generic terms, and will insert the Cultural equivalents.
I'm working on the equipment now, and there is a TON of previous works I am drawing from. I also hope to give some sample spreadsheets in the future.
I've actually done a cast on how to use my spreadsheets, particularly for the Mongoose Traveller. I'll upload it on this blog once I have the chance. I plan to show how to use my spreadsheet tools this way, since its me explaining stuff without me in the picture like in Khan academy.