Skill check mechanics

Do the characters actually need to test skills in this numerical fashion? It sounds like the enemy is going to be really speeding along so maybe the players skills should just be actions they can take to try to interfere with the enemy progress, and by limiting the number of actions they can take per turn you're asking them to 'test' their skill by deciding where to gamble on leaving a threat until the following turn.

Some example ideas (which may or may not be relevant because I can't tell too much about your game):
- A thief or magician character could have a 'Sleight Of Hand' skill that lets him swap the negative chits you mention between different threat cards in his room; he doesn't eliminate a threat but he can influence which is the biggest danger.
- A warrior type could remove up to his current strength in chits from a single threat as long as he doesn't move this turn. If he reduces the chits to 0, the card is removed from the room.

The 'test' for these guys is do I use my skill this turn for a partial benefit or do I wait until next turn when I can get the full benefit but I'm risking a card or encounter that makes things too bad for me to handle?

If you do want to stick with skill checks, any of the methods you mention are perfectly reasonable, just make sure you test them a lot to ensure the level of difficulty is correct. An alternative might be to give players action points which they can spend on their skills for a particular level of efficiency so maybe spend up to 6 action points and then roll 1d6; if you roll equal to or less than the action points spent you succeed. If you limited players to 10 action points per turn this would give them a lot of hard decisions but would also allow them to choose to succeed at critical checks rather than get screwed by the luck of the die.

I hope something in this long ramble is useful!

. . . kind of like Shadows over Camelot?

Color dice or dice with symbols on the face represent another option. Memoir '44 uses symbols and I'm developing several different games using color dice.

For example, suppose you have 6-sided dice with the following faces:

Shield (defense)
Bullet (attack)
Star (special)
Question Mark (wild)
Blank (no effect)
Blank

Different skills would require different combinations of results. For instance, assuming you roll 3 dice:
Sneak Attack (do one point of damage no matter what opponent's defense) = Bullet + Star
Dodge (avoid all damage from one attack) = Shield + Shield
Purify (instantly destroy one lesser monster) = Star + Star + Star

To adjust difficulty, just change the number of dice rolled. 3 or 4 dice would be "baseline" -- opponents are even. As the opponent gets easier, add dice; harder, remove them.

Color dice work similarly.

Color dice would work similarly.

Cool to know that we are working on a similar game.

You can also look at many RPG for inspiration.

In order to design a skill check, you need to consider many factors:

A: Is it going to be a contested roll ( 2 rolls opposing each other) or is it going to be 1 roll vs a target number.

B: How many variables in going to take part of the roll. In a Arkham Horror system, you can influence the roll by changing the number of dice rolled, the target number required to make a hit and the number of hit to succeed. So in a system like this, you can insert 3 different variables.

C: What are the Value ranges? In s system where you roll X dice and add bonus Y, you could end up in a situation where some rolls are impossible or always succeed. For example, it is impossible to roll 12 or more with 1d6+4 while rolling 4D6+8 is an automatic success.

D: Does the amount by which you succeed has an impact on the results. Ex: Exceeding your TN by 5 points gives a bonus effect.

E: Are there going to be situational modifiers that gives bonus/malus or that raise/lower the TN.