Nowhere is completely safe. War is always a threat. A chance encounter with another player could be the end. Careful, though - killing players will put a bounty on your head, and bounties are worth XP rewards.
+ RPG Elements
Level up your skills to unlock special abilities. Level up your mana to use them. Enchant your weapons with custom enchantments and use your power to fight off challenging mobs, or summon a boss and defeat them to earn rewards.
+ Hard Difficulty
Zombies can break through wooden doors and spawn reinforcements. Spiders have beneficial status effects. Villagers turn into zombie villagers when killed. Hostile mobs deal more damage. Starvation kills.