Vampire: The Masquerade—Bloodlines was based on the tabletop RPG Vampire: The Masquerade. The videogame's protagonist was defined by the same skills and abilities, and its vampiric clans used broadly the same disciplines. But the pen-and-paper original has moved on in the intervening years, and is now up to its fifth edition, released in 2018.
In the latest dev diary for Bloodlines 2 (opens in new tab), lead UI/UX designer Rachel Leiker explains how they drew on those newer rules for the videogame version, and some of the places they differed. For instance, in Vampire fifth edition, blood has four emotional 'resonances', each of which can affect different abilities when drunk. Bloodlines 2 bumped that number up to five, and changed how the bonuses work.
As Leiker writes, "Delirium, Desire, Fear, Pain, and Rage are all emotions that can be discovered and devoured in the game and act as a secondary XP to unlock and activate Resonance-specific buffs, or Merits. The Resonance and Merits in Bloodlines 2 are more rigid in their implementation, but they allow players to quickly hunt for and manage the resource throughout the game."
Since the game's protagonist starts out as a 'Thinblood', a vampire without access to normal clan disciplines, the designers wanted to round out the abilities available to them. In the pen-and-paper game Thinblood Alchemy lets them temporarily counterfeit any other clans' powers, and for Bloodlines 2 they chose three to focus on.
"The three Thinblood Disciplines – Chiropteran (Affinity to Bats), Nebulation (Mist Form), and Mentalism (Telekinesis) have mostly traversal and defensive applications. Thinblood Alchemy in V5 is much the same way – Thinbloods are at the very very bottom of the food chain, so survival is the number one priority. We maintain the core feeling of what it means to be a Thinblood and use those powers but make it more video game friendly by expressing it in familiar ways. Who doesn’t want to glide across the Seattle skyline, travel as mist with the wind, and move objects without touching them?"