Normally I wouldn't touch the resolution system of a game ever, but the one in A Time of War seriously drives me nuts. I find the "modified roll versus a fixed target number" to be a little harder to headmath than modified target number systems like in many other games (BattleTech proper, GURPS, Warhammer Fantasy Roleplay 1E and 2E, and numerous others.)

You could do a "modified target number/roll over system" with AToW, which would make it exactly like BattleTech, by inverting the bonuses/penalties and applying them to the target number instead of the roll. However that requires having to remember to invert the sign of every single modifier in the entire book because unlike BattleTech, AToW was designed with "positive is good" in mind, while negative is good in a system like that.

I decided that I'm going to give a "modified target number/roll under system" a try which would preserve every bonus/penalty exactly as written. I'd like to run it by everyone here just in case I made any mistakes. There are only a few changes:

**New target numbers**

Single attribute check: 2

Double attribute check: -4

Simple-Basic check: 7

Simple-Advanced or Complex-Basic check: 6

Complex-Advanced check: 5

Consciousness check: 7

Anything else: 14 - (original target number)

Any situation where a target number is modified (such as Phenotype Field Aptitudes): Invert the sign of the modifier before applying it (negative becomes positive and vice versa)

**Doing a check**

Take the applicable target number, add all bonuses to it and subtract all penalties from it to get the modified target number. Roll 2D6 and a roll equal to or lower than the modified target number is a success. Margin of success/failure is just the difference between the roll and the target number as usual but with signs swapped.

2 is a Stunning Success. Roll 1D6 and subtract it from the effective roll and keep going as usual if you roll a 6.

12 is a Fumble.

Everything else in the Basic Gameplay chapter, and the rest of the book, should hold. The results of the rolls (probabilities, margin of success/failure, etc.) should be absolutely identical and shouldn't affect anything else.

Did I screw up anywhere? I'm going to be giving this a try in the future and I don't want there to be anything freaky going on.

Edit: Examples of how this works:

Single attribute check against Charisma with a score of 5: The base target number is 2. The modified target number is 2+5=7. You roll a 5, giving you a success with a margin of success of 2.

Double attribute check against a Strength of 4 and a Dexterity of 5: The base target number is -4. The modified target number is -4+4+5=5. You roll an 8, giving you a failure with a margin of failure of 3 (or -3, if you prefer to put a sign on it.)

Skill check against Perception with a score of 2 at a distance of 500 meters (-1): The base target number is 7. The modified target number is 7+2-1=8. You roll an 8, giving you a success with a margin of success of 0.

And so forth. It front-loads all the math before the roll, which makes you think less about whether the roll you just made was a success, and makes it a little easier to figure out probability of success before choosing to make the roll.