Simple and intuitive rules are the best in my opinion. Complex rules discourage new players and for a new TTRPG mean a hard to captivate game. I like the way the PBTA game do it. An intuitive rule's system with 2d6 to solve a combat, that is action based, cinematic and fast and more based on narrative instead of math. Apocalypse is a very popular, and you can create a new narrative from it.