If you’ve played Baldur’s Gate before, the basics are the same: both games use the second edition AD&D rules, although, in Planescape: Torment’s case, some aspects of combat have been simplified. You’d think that this would make your life easier…but it doesn’t, really. Or, at least, not consistently. That being said, there is so little combat in the game that it doesn’t much matter in the end.
You can have a maximum of six characters in the party, although this also means that EXP will be split between that many more people. You can select the entire party for travelling purposes and assign a battle formation of your choice. This is where you encounter the first unnecessary simplification: The Nameless One will always be the leader, meaning that he will always be on the front lines, regardless of the chosen formation. Needless to say that this is dangerous for Mage TNOs.
You can take manual control of each character, like in BG, to issue specific commands. However, unlike in BG, these commands are accessed via a radial menu, which shows up when you right-click on the character in question, rather than appearing at the bottom of the screen. I find this unnecessarily fiddly, but it’s not exactly gamebreaking. What’s more problematic is that PST doesn’t let you modify the characters’ A.I. to your liking, like BG did. So if you’re unhappy with their default script, your only recourse is to turn the A.I. off for the entire party.
Combat happens in real-time, and all enemies are visible on the map. This means that you could make Annah (or a Thief TNO) hide and scout ahead, just to make sure you don’t run into anything nasty unprepared. Battles are subdivided into six-second ‘turns’, which are individual to each character (the timer starts from the moment you select an action for that character). Depending on their class and weapon proficiency level, they’ll deliver a different number of attacks per turn.
The main characteristic of second edition AD&D rules is a numerical reversal: the lower a character’s Saving Throws, Armour Class and THAC0, the better. So, for example, a 1 is better than a 5 and a -1 is better than 0, and if a piece of equipment gives a “+1” bonus, it will actually lower the corresponding number. Saving Throws–the name is a remnant of the game’s pen-and-paper ancestry–are what determines a character’s resistance to various types of attacks (e.g. missiles) or negative effects (e.g. poison). Armour Class (or AC) indicates how hard a character is to hit, while THAC0 (“To Hit Armour Class 0”) indicates how likely a character is to hit an enemy whose AC is 0. If a character’s Dexterity is 15 or higher, they gain an AC bonus. If their Strength is 17 or higher, they gain a THAC0 bonus. Additionally, for ranged weapons, another THAC0 bonus is granted when Dexterity is 16 or higher, although, in this game, this only really concerns Nordom. Unsurprisingly, weapon proficiency also affects THAC0, as well as damage dealt.
Dual- and multiclassing concerns have been entirely dealt away with, as, despite technically being human, TNO cannot dual-class, unlike in BG. Annah and Dak’kon are both multiclassed, but since they’re companions, you have no say in their raw stats, only their abilities. On the one hand, it does spare you some hassle in terms of character creation and subsequent management, but on the other hand, it limits your versatility in combat and forces you to deal with constant class switching for stat bonuses anyway, and several times instead of just once, at that.
In terms of magic, there are two spell schools: arcane magic for Mages and divine magic for Priests (or Priest, since Grace is the only one). Each school includes offensive, beneficial and indirect spells, although the divine school is more focused on defence and healing, while the arcane school is more focused on damage and debilitation. Divine spells are learned automatically, while arcane spells need to be scribed from scrolls or learned from items. Additionally, depending on the Mage’s Intelligence, scribing a spell may fail, in which case, the scroll or item used to learn it is lost (…why?), so you need to make sure to save before scribing. In BG, another restriction would come into play here, as divine spellcasters are not hampered even by heavy armour, while most armour impedes arcane spellcasting. In PST, all such concerns are moot, since Dak’kon wears his own armour, specifically suited for spellcasting purposes, and neither Ignus nor TNO can wear any armour at all.
However, the biggest limitation on spellcasters still remains, that being the number of spells they can actually cast. Since there was no such thing as MP or mana back in the day, spells were subdivided into increasingly powerful tiers (higher tiers opening up as the character gained levels), with only a certain number of spell slots per tier. In order to cast, Grace or a Mage must first select the spells they want at their disposal into these slots, then rest in order to ‘memorize’ them. If they want to change spells, or once they’ve exhausted their arsenal, they must rest again. This is already annoying per se, since it forces casters to conserve their spells for more difficult encounters, meaning that they’ll want to resort to attacking easier enemies the old fashioned way. Not a problem for Dak’kon, who has a sword and some decent armour, or Ignus, who has fireballs, but it’s a whole other story for Grace or a Mage TNO, who will need to get into melee range without adequate protection. On top of this, there’s also a dearth of safe resting spots in the game, which makes spell management even more of a hassle.
One last nitpick: simply looking at the spell lists is enough to realize that combat is really more of an afterthought in PST. Some of the higher tiers of magic only include one or two spells, and several high-tier arcane spells have been cut from the game. It’s not that I really mind, but it feels…sloppy.