OK, initiative bogs things down. My system below is too complicated as is, but it is a starting point to revisit later. The just: Everyone has an initiative number that is calculated. Then weapon and situational mods are added. Base initiative is your Dex mod. Medium armor subtracts 1 Heavy armor subtracts 2 Fighter types add 1 per 4 levels Rogue types as 1 per 5 levels Scholar types add 1 per 10 levels There would be some feats that add to the above. If you are surprised a big minus for the first round would apply. Anyway, you come up with a number. That doesn't change. Monsters and foes have a number. That doesn't change. You do in the order of highest to lowest.
I've seen a lot of 1 page or 4 page RPGs out there. Some of them are pretty neat. Most of them I would not consider complete RPGs. Why? I started thinking about that. What makes a complete RPG anyway? Here are some bullet points to be flushed out later. Complete mechanics: Character creation, character advancement, and action resolution rules. Equipment List Spell List (if applicable) Vehicle/Animal rules,Travel, Encumbrance, Food mechanics. Fiend / Antagonist Folio Samples of how to use all of the above That is about it. Note the first bullet point is the core game. How do I do x? How do I know if I can do x? I'll flush this out later. But those I think are the core.