Initiative and Rounds¶

Baldur's Gate follows AD&D combat rules closely but with a real-time adaptation: each character, NPC, and monster runs on its own six-second personal initiative round.

Personal initiative round¶

Within each personal round, the full AD&D ruleset applies — weapon speed factors, casting times, multiple attacks per round, and so on. For higher-level characters who get more than one attack per round with a given weapon, the weapon's speed factor determines when in the six seconds each strike lands.

Speed factor¶

A weapon's speed factor is a number from 1 to 10 representing tenths of a round (1 = fastest, 10 = a full round). Lower is faster.

Casting time¶

A spell's casting time is the spellcaster's equivalent of a weapon's speed factor. Casting times range from 1 to 10; the lower the number, the faster the spell is released.

Initiative¶

Initiative combines ability, situation, and chance. In Baldur's Gate it acts as a random variation that slightly nudges the casting time or speed factor of an action — so two characters using the same weapon won't necessarily strike at exactly the same moment.

Hack and slash isn't everything¶

Combat isn't the be-all and end-all of play. Beyond simple hitting and missing the rules cover:

Turning undead.
Special attacks and defences.
Poison and disease.
Heroic feats and class abilities.

Any time you want, you can pause the game to assign commands and then unpause to resume.

Source: bgee/original_manuals/baldurs_gate_1_ee_mastering_melee_and_magic.pdf — "Combat in Baldur's Gate" → "More than just Hack and Slash", "Personal Initiative Rounds", "Speed Factor", "Casting Time", "Initiative".