I vastly prefer an RPG book with a layout meant to facilitate use at the table rather than written like a book with blocks of paragraphs.
If you are looking to GM for the very first time or just looking for a new table top RPG to run, you can try out Mutant: Year Zero using just a free PDF and some spare six-sided dice you scavenge from board games.
A variety of RPGs provide mechanical effects that affect the use of violence in a game.
Your character kills a kidnapper and saves a child. Do you roleplay the effect that killing has on your player character?