"Would" conveys a subjunctive, or conditional, meaning. "I would be alone" implies an unspoken qualification such as "if that was possible" or "if I had my way."
"I would be alone" sounds archaic. It recalls Shakespeare's work for many students, and it is sometimes used to suggest an Elizabethan style of diction. In fantasy fiction it is sometimes used to imply the speaker comes from a chivalric or royal court culture, typically English, sometimes French, and, strangely enough, sometimes in shows with supernatural themes (witches, werewolves, demons). As a result, it is a trite construction in popular entertainment, and is a common target for mock usage as well.
Modern use isn't that different in meaning, but in application. "I would like a beer," for example, is common. Add in the implied "if you have one" or "with your permission," and it can sound timid or deferential, but most people do not take note of that and consider it synonymous with "I will have a beer."
You'll hear a lot of this form in political rhetoric, as it implies an important prerequisite to the intention. "If elected, I would institute a flat tax." You'll also hear it, perhaps not coincidently, as a way to avoid lying without actually countering an allegation or circumstantial evidence: "But I would never steal from my boss because stealing is wrong, and I would never do a wrong thing."
It's also used to suggest an alternate outcome if the conditions of the moment were somehow different. "I would cap my reputation every day if everyone would just wait for my answers."