The original BG2 use AD&D rules, where a round is 6 seconds, same as always (A turn is 60 seconds) and you only have one movement, one action in the same round.
"The number of actions a character can accomplish in one round, i.e, in six seconds of real time, is limited. Some actions can only be performed once per round. These actions are: casting a spell, using a quick item such as a potion or a scroll, using an ability from an equipped item such as the Cloak of the Sewers' polymorph, or using an innate ability like the Kensai's Kai or a Spell Trigger. In any given round, it is only possible to use one action taken from all categories combined. It should be noted that the wizard spell Improved Alacrity lifts this restriction for spells and innate abilities, which can then be used at will"
AD&DD&D5e uses a 6-second round system where a creature has one movement action, one standard action, one bonus action and one reaction action in the enemy´s turn on the same round. You have the same number of actions per round in the videogame.
D&D5e
