HaShem

There is a person's literal name and then their reputation.  Both are sometimes referred to by the word name.  When the Torah says to not use God's name in vain or to not misuse God's name (Exodus 20:7, Deuteronomy 5:11), it would be addressing the latter because the word God is not a name.  It is a word for a category of metaphysical being.  Some Jews, hoping to avoid misuse of God's name, call God HaShem (meaning "The Name") and write out the term G-d, as if to use the full word is itself blasphemous.  HaShem effectively becomes another name for God rather than a substitute, for it is used with the intention of referring specifically to the Biblical Yahweh rather than even a more general, unspecified theistic being.

Blasphemy is cursing God (Leviticus 24:11), not directly referencing him, and thus not by using the word God aloud or in written form without the hyphen replacing the letter o.  God is not a name left to itself anymore than general or president is a "name," though the word can be used like one, similar to how "dog" can be treated like a name if used to address a particular dog.  God is a word for a very precise metaphysical category rather than the actual name of a specific deity, so it is in no way a name on its own.  This necessitates that some utterances of "Oh my God" are blasphemous solely because of the intention behind them and not because of the words themselves.  Other such utterances are entirely nonsinful by genuine Biblical standards.

The basis for the tradition of using HaShem is in turn about using an utterly unnecessary name or placeholder for a name as far as Biblical morality goes.  Someone could use the term God, even saying something like "god damnit," and not mean by it anything derogatory about the real uncaused cause or the Judeo-Christian deity particularly.  This could not be any sort of direct offense against Yahweh in this case either way because it is not a slanderous or malicious statement in itself.  To use HaShem out of personal preference, knowing the distinction between non-obligatory but permissible habit and actual Biblical duty, is permissible.  Pressuring other people to use the word HaShem is itself a violation of the Torah's moral philosophy (Deuteronomy 4:2, 12:32) and would be even if there was no explicit command to not add to God's instructions.

The Torah does not require that any particular name for God be used, including substitutes that ultimately are treated like names even though they are more like titles or epithets.  A person is free to just call God by the word God, intending to reference the deity of the Bible, or to call him by names like Yahweh or Jehovah.  There are no inherent prohibitions on what to call God as long as one has the right philosophical ideas in mind.  After all, human words have no inherent meaning, for the speaker intends something specific by them and that is their meaning in a given case.  Even pagan names like Baal or Athena are just arbitrary linguistic constructs and could have been associated with Yahweh had the historical development of culture and language been different.

Using God's name in vain is not saying "Oh my God" as some Christians assert.  It is also not using the word God to accurately, respectfully address or speak of Yahweh, or using any of the conventional names for the Biblical deity.  Using God's name, or "name," in vain is to ascribe philosophical falsehoods to God or to be dishonest in the name of Yahweh (this phrasing, of course, is not about literal names at all).  HaShem, Yahweh, the God of Abraham—it would not matter what he is called of these or many other words.  Carelessly making oaths to or about him (Deuteronomy 23:21-23), speaking maliciously about or to him (Leviticus 24:10-16), and lying selfishly as if on God's behalf (Leviticus 19:11) are the ways to verbally misrepresent his character or curse him.