Combat is tick-based. Your max hit and accuracy come from your effective levels and equipment bonuses: melee max hit is floor(0.5 + effectiveStrength × (strengthBonus + 64) / 640), and hit chance compares your attack roll against the target's defence roll. Choose a combat style before fighting: Accurate (+3 effective Attack), Aggressive (+3 effective Strength), Defensive (+3 effective Defence), or Controlled (+1 to Attack, Strength and Defence). Auto-fight keeps killing the same monster, banking loot as you go.
In the open world, any monster you have engaged keeps chasing you if you back away instead of resetting on the spot — and if it catches up, it starts swinging again on its own. Stepping back buys distance, not a free reset; only leaving its reach for good, or leaving the area, actually ends the fight. Walking away yourself still stops your own attacks until you tap Attack again — only the monster's swings resume automatically. Kills out there count for everything a kill in the idle game counts for: your slayer task advances, your daily tasks fill, and rare drops fill their collection log slot. Every monster you kill builds a kill count, in the open world and in the idle game alike — not just bosses — so the grind is on record wherever you do it. Fighting something alongside another player follows the same rule a group boss does: deal at least 10% of its hitpoints and the kill is yours — its drops, the kill count, your slayer task and your daily tasks. You each roll the drop table for yourself, so two people who both cleared the line get two separate piles on the same tile, and neither of you can see or take the other's. After about a minute anything still lying there goes public and the first person to reach it can take it.