VPS with TNs
In the existing VPS system, players roll a d20 and compare the result to their character's Trait+Skill, trying to roll under or equal to that sum but as close to the sum as possible. In addition to being sometimes difficult to understand, this system leads to a lot of failures -- an "average" character with a 5 trait and a 5 skill will fail 50% of the time.
Instead, we have characters roll a d20 and then /add/ their Trait+Skill, comparing the result to a Target Number based on difficulty.
DIFFICULTY TARGET NUMBER Easy 10 Moderate 15 Hard 20
VPs and successes are based on the number of points a player's roll exceeds the target number on the same chart as ordinary VPS -- so a character who rolls a 23 on a Hard roll gets 1 VP, a character who rolls a 31 gets 3 VPs, and so on. A character who rolls the TN exactly has an automatic success; a character who rolls a natural 1 has a critical failure, and a character who rolls a natural 20 has a critical success. We've eliminated automatic failures from the system.
The chief virtues of this system are its ability to handle rolls involving spirit traits better, as they are usually lower than other traits, as we can just set a lower TN for spirit rolls. Similarly, the system can handle the distinction between Learned Skills and Natural Skills with TN differences -- in a situation where the characters are searching a deserted village, for instance, the GM could call for characters to roll Perception+Search at a Moderate difficulty or Perception+Observe at Hard.
All combat rolls continue to be at Hard difficulty, which preserves almost exactly the success rates from the VPS system in the core books.
Occult rolls are almost always at Moderate difficulty, as they are usually based off Spirit traits.