Characters are the heart and soul of a roleplaying game. They may be controlled by players, a game master or the computer; they may be blank slates, or have a cool name, detailed personal history and colorful description, with a portrait to match. Either way, to the rule system they are a set of attributes that determine what they can do in the game and how well. In Battles&Balances, you're not just a number, you're half a dozen numbers, and then some.
First of all, any character in this game has a size. The size is always an even number, usually between 4 and 12 (because you'll have to roll dice for it, and divide it by two in some situations). Humans are represented by 8-sided dice, abbreviated as d8. Sizes don't have to respect proportions though! They're more like a rough indicator. Also consider other factors, like build. For instance, generic fantasy dwarves may be shorter than humans, but they're also broad and solid, while elves are taller, but also thinner; both would be a d8 as well, with the differences captured by attribute scores.
Speaking of which, apart from their size, characters have five attributes:
Each attribute has a score, usually between 2 and 4, with a score of 1 best left to characters with a disability, and 5 meaning "peak (insert species here)". A score of 6, if you insist, is fit for a demigod; by the time they have scores in that range, humans are fighting d20 dragons and giants because no lesser creature can provide a challenge.
Other, secondary scores are derived from the ones above:
You may have noticed that being bigger gives an advantage in every regard, including speed and focus. This may seem counter-intuitive, but think of it this way: all else being equal, larger creatures have bigger eyes and ears, and longer limbs. Attribute scores can be used to account for differences.
Let's define a few different characters and see what they look like:
**Chief Adunc, envoy of the Underground Committee** Dwarf (d8) Muscle: 4, Stamina: 4, Agility: 2, Speed: 2, Focus: 3
While not exactly a warlike race, dwarves deem it important that each of them can fight to defend themselves and their own. Tasked with a peaceful mission, Chief Adunc isn't especially adept at hitting an enemy... but he only needs to land one blow. And he can take a lot more than that.
**Prince Vasyl of Ostgrund** Human (d8) Muscle: 4, Stamina: 2, Agility: 4, Speed: 2, Focus: 3
One would be fooled, seeing his girth, but the prince is also a skilled fighter in addition to a good leader, which has helped earn the respect of his soldiers. Not exactly fast or resilient, he makes up in skill and training. And tactics, but that's another story.
**Jinx the Thief** Elf (d6) Muscle: 2, Stamina: 2, Agility: 4, Speed: 4, Focus: 4
Legend has it that Jinx was really a powerful sorcerer from a distant shore. Stranded in the port city of Costamata, penniless, hungry, ignorant of local customs and language, they were forced to live on the streets for a while, and would still return sometimes to help people in need.
(Note how Jinx gets an extra attribute point to compensate for smaller size.)
As for how to let the player choose, there are several ways, such as offering them predefined characters or giving them a number of points to distribute at will. But I found it easier to make every character a weakling or at most average at first, to leave plenty of room for growth.
Most games have characters of some sort, but only in RPGs it's essential that characters develop as time passes, gaining new abilities and getting better at those they already had.
How to achieve that is another story. Growth can happen in more than one way. And the most obvious is increasing the attribute scores we've discussed already.
The question is when. It can be as simple as letting the player increase an attribute of their character by one point at key moments through the game. More flexible is to grant them a number of experience points for reaching the same milestones, and let them spend those points at will. E.g., making each upgrade cost 1000 XP, and handing out 200-300 XP for a minor objective, with another 100 or so on average for each enemy defeated, means the player can "level up" their character every three story beats.
Of course, that means a linear increase, but even if you make XP harder to come by as time goes on (after all, you're not going to learn as much from killing the 57th giant cockroach as you would from the first), 15000 XP later every Steve Rogers turns into a Captain America -- the best at everything. And in a party-based game, it means the player characters will keep stepping on each other's toes. If you want a game to last longer, you'll need to space out those story beats... but that means slower progress, which in turn can feel unrewarding.
To solve that problem, in-between more significant upgrades, you can give them cool new toys to play with. And that means equipment.