Attributes represent the points you have to spend to use skills. For example the fighter will have the 'stamina' attribute because most fighter skills need a certain amount of stamina. Wizards will spend mana to cast spells. Attributes recharge at a given rate so that you can't endlessly use skills. The more powerful skills consume most of your attribute points so you have to use them with caution.
Here is a list of jobs currently on my mind. The first release of TCOD will only feature the fighter job.
He's the first because he only needs the basic game mechanisms and melee fight. He's specialized in the use of melee weapons and armors, has a lot of health points and deal a lot of damages. His weak points : he's not too good at stealth and have to reach melee range to attack a target.
For this one, I'll have to add ranged weapons and distant target selection to the game engine. He can move by stealth and deal damages to targets while staying out of range of their attacks. His weak point : once at melee range, he'd better run away...
The two next will feature the first magical skills.
He's a wizard specialized in the fire magic. His tactics are to deal the maximum of damages at distant range so that enemies can never reach melee range where the he would become vulnerable.
He's a wizard specialized in the water magic. While dealing less damages than the pyromancer, he can slow down or freeze enemies and protect himself with ice armors.
For this one, the game engine must be able to manage computer controled sidekicks. The necromancer is specialized in summoning creatures from corpses.
While being classics of the RPG genre, those jobs are not choosen arbitrarily. Each of them provides a very different gameplay experience.
From this point, I'm not yet sure where the game will evolve. Maybe I'll keep on stealing good ideas from Guild wars by adding mercenaries and/or heroes.
Mercenaries are NPC you can temporary hire to fill some of your weaknesses.
Heroes are NPC that go with you during a longer time. You manage their equipment and their XP progresses as yours.
There is also the possibility to add non combat jobs that give crafting skills. I've always been impressed by the Star Wars Galaxies crafting system where you don't only have to find a certain quantity of metal to build a sword. In fact, there are lots of different types of metal and each one has different characteristics. Some will make you sword stronger so that it has a better durability. Some will make it sharper so that it deals more damages. You can also mix several types of metal to build the sword perfectly adapted to you needs.