There are three alignments, Law, Chaos, and neutrality. However, neutrality is an agnostic or transitional state between the other two. One can ally with the forces of Law or of Chaos, or attempt to remain neutral. Chaos and Law constantly battle over the allegiances of men and other species. Some supernatural entities also attempt to maintain neutrality in this war, with greater or lesser success, but they tend not to interfere in power struggles or gift powers to mortals.
Those allied to Law or Chaos are granted a type of supernatural language. To speak or understand Law, you must be aligned to Law. The same is true of Chaos. If you ever drift away from your allegiance, you will lose the ability to speak/understand the language. The range of concepts communicable in these languages are related to their nature. For instance, there is no word for “truce” in Chaos; but one may speak of a bargain.
Speaking Law or Chaos is a powerful and often dangerous act. It may reveal your presence to supernatural creatures. It will certainly be recognized by enemies and can be used as a kind of litmus test among allies. Characters who are exposed to an alignment language they don’t know for very long will suffer, physically and mentally. Anxiety and headaches are followed by tears of blood or other stigma. If the exposure is prolonged, madness may result. Characters who are neutral will suffer less than those of the opposite alignment to the language being spoken.
Some spells are scribed in alignment language. This means that they may not be cast by individuals of other alignments without the use of Read Magic and without sustaining damage and eliciting the attention of supernatural beings. (It also means that despite being magic, someone of the same alignment could read it without using Read Magic.)
[Rules text for OSE. Still noodling a little over the specifics and they may evolve at the table.] Suggested damage for exposure to an opposite alignment language is d3 hp per round (1 hp for neutral characters) If the exposure is prolonged or especially intense, the GM may call for characters to Save vs. Spells to avoid madness. On a successful save, the damage ends . Characters can try to drown out the voice of someone speaking by making loud noise or even speaking loudly in the opposite language. Combining voices of the same language don’t do additional damage, and Chaos and Law being spoken at the same time cause a painful noise but essentially cancel each other out other than probably calling every servant of Chaos and Law within psychic earshot.
Speaking an alignment language requires concentration. Characters and move and speak, or speak and attack or cast, but can’t move, speak, and attack/cast. The damage for casting a spell in the language of another alignment is d3 for neutral casters and d6 for casters of an opposed alignment, for each level of the spell.
Common is a trade language based on the most common, wide-spread human dialect. Most humans know Common and, as does any species that commonly interacts with humans.
Common consists of about 800 very basic words. It is pretty easy to learn, but lacks any depth or nuance. For most things, there is only one word: e.g. “home” covers house, hut, den, burrow, nest, etc.
Species with mouth-shapes that significantly vary from human are less likely to (be able to) speak Common. Communication with such a species takes longer (requires more patience) and is likely to include a number of misunderstandings from concept drift or simply misspeaking/mishearing.
Speaking to another culture in their own language automatically gives you a +1 on reaction rolls. It probably also gives you a rudimentary understanding of their culture.
Some folk refuse to learn or speak Common. Usually their reasons are seated in some form or cultural/regional pride and/or dislike of other species. Speaking Common to them may cause a -1 reaction penalty.
Languages other than alignment can be learned through study. Speaking a language may require a mouth similar to the species whose language is being studied.
Languages are often related to each other. Given a steady stream of nonverbal cues, context, and words, a bystander can sometimes follow the gist of a conversation by others if the language being spoken is close to any they know.
The INT bonus determines how many additional languages (other than alignment, native, and common) a character can learn. These languages may be chosen from the list below during character creation or they may be saved for learning a language later. Adventurers aren’t scholars and simply don’t have the time to study/learn an endless number of languages. If a character wants to learn a language at some point and doesn’t have any open slots left, they may study to learn a kind of smattering or pigeon form of that language. Mark it with an asterisk on the character sheet to indicate its limited nature. To change languages, mark an old one with an asterisk (the character is extremely rusty with it) and fully learn the new one.
Your list here.