Making Dodge-Crit a single roll and also cancel each other?

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Autoclave
Posts: 48
Joined: Wed Mar 01, 2017 8:00 pm

Making Dodge-Crit a single roll and also cancel each other?

Post by Autoclave »

How can I change the system where Dodge and Crit a two separate rolls? I want it to be one roll with a clear and simple rule and easy to understand and for the player.
nmkaplan
Posts: 207
Joined: Thu Jan 26, 2017 5:14 pm

Re: Making Dodge-Crit a single roll and also cancel each other?

Post by nmkaplan »

My understanding is that Dodge and Crit are *treated* as two separate rolls, but in actuality are not. The XCom 2 system only allows for one attack roll, so the conditional probabilities are just crunched together and included on the single roll.

Example: 80% hit, 50% crit, 20% dodge. No graze band (for simplicity).

How you seem to imagine it works:

Roll to hit: (80 hit, 20 miss)
On hit, roll crit (50 crit, 50 no crit)
On hit, roll dodge (20 dodge, 80 no dodge)

How it actually works:

Crunch numbers:
Normal hit - (.8hit * ((.5no crit *.8no dodge) + (.5crit * .2dodge))) = 40%
Crit hit - (.8hit * (.5crit * .8no dodge)) = 32%
Graze - (.8hit * (.5no crit *.2dodge)) = 8%
Miss - 20%

Then the game makes 1 roll with those probabilities. There are no actual 2nd and 3rd rolls for crit and dodge. The game just pretends there are and adjusts your probabilities on the 1 roll you do get accordingly.

Xcom2 Vanilla had 1 roll with simple rules that were easy to understand, but the result was that the gameplay suffered (ie. "10% hit, 10% crit" was actually "10% hit, 100% crit" because hit% and crit% overlapped). Advent troopers were taking low percentage shots, and the ones that hit would ALWAYS crit. Not a great scenario.

In XCom EU/EW the rolls were separate as in LW2. It's just that there was no "graze" mechanic so the dodge stat didn't exist, making it much simpler to understand.
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