So basically Pathfinder was 3E but they tweaked a few rules like with the Sneak Attack? and its still a decent game imagine that.
No, pathfinder kingmaker changed the sneak rules.
In PnP you apply sneak attacks when the enemy is flanked or the enemy cannot see you or cannot defend himself.
The importent part is how flanked works.
In PnP a character is flanked when 2 characters engage an enemy in melee AND IF YOU DRAW A LINE FROM ONE CHAR TO THE OTHER THE LINE MUST GO THROUGH THE ENEMY.
The enemy is only considered fanked for the characters who engage the enemy in such a position.
In PK an enemy is considered flaked WHEN HE IS ENGAGED BY 2 CHARS AND THEN IT IS CONSIDERED FLANKED FOR ALL CHARS:
So when an enemy is attacked by 2 melee chars (including pets or summons) all characters can add sneak damage with any attack, including ranged attacks and spells.
example: E = enemy, M = melee chars, R = ranged character
E R PnP: nobody is flanked, PK: enemy is considered flanked for all chars
MEM R PnP: enemy is considered flanked for both melee chars only, PK: enemy is considered flanked for all chars
Edit: The text ignores several space in a row. In the first example 2 melee chars attack the enemy from the same side while the ranged char is far away.
In the second example The melee chars attack the enemy from opposing sides and the ranged char is far away.