Crits can't be dodged or parried though, so the scenario would never happen, unless I'm remembering rules wrong

IIRC by default you can attempt to dodge any attack, regardless of how many Wounds (positive or negative) the PC has. The one you might be thinking of is the Killing Strike talent (a starting ability of all Astartes), where if you make an all-out attack and spend a Fate Point, your hit cannot be dodged or parried.

No, I don't remember where I read it but you can never dodge or parry a critical sucess, no matter what. It may be a house rule from the group I started playing tabletop in over a year ago, but I have died more than once to a critical success by the hands of an enemy

For long range + shots, I require pcs and no a to first pass a free awareness test with a modifier of -5 for every 50 meters away the shot is coming from. I don't believe you can dodge a sniper your not aware of. Just a random thought that came from the earlier portion of the discussion.

No, I don't remember where I read it but you can never dodge or parry a critical sucess, no matter what. It may be a house rule from the group I started playing tabletop in over a year ago, but I have died more than once to a critical success by the hands of an enemy

Never heard that before. Thinking about it, normaly you roll dodge/parry before damage is rolled, so how will you know if it's a crit?

Regarding the sniper shot Cogniczar is talking about, isn't that what (among other things) rapid reaction is for?

Hmmm, he's talking about Critical Success , not Damage, like I first thought. It's not a concept found in the DW books, but it wouldn't be a surprising houserule if the GM were to decide that rolling 01 means an undodgeable (is that even a word?) attack, while 00 means an automatic failure.

No, I don't remember where I read it but you can never dodge or parry a critical sucess, no matter what. It may be a house rule from the group I started playing tabletop in over a year ago, but I have died more than once to a critical success by the hands of an enemy

That sounds like something from BRP or Eclipse Phase, both of which had some sort of critical success/failure as determined by the attack roll. In particular the EP version was that on opposed tests (such as dodging), a critical success (success + doubles on percentile dice) trumped a standard success (no doubles). But at least in that case, if your roll was still better irrespective of the critical then you could spend Moxie (comparable to Fate Points) to upgrade a standard success to a critical one.

By critical success, I mean 1-5. Crit fails for my group are also 95-00. Crit fails result in jamming/dropping/shattering a weapon, dodging INTO an attack (meaning it bypasses 2 points of TB), or something particularly nasty. A crit success means an attack is undodgeable, or the next turn you get a +5 to attack the enemy on a dodge/parry, with a 1 on a parry resulting in the enemy dropping their weapon.

Yeah, that's definitely a houserule. Some of the results are rather random for my taste, but if your group enjoys it then more power to you.

I actually tried making Dodge and Parry an Opposed Tests. Unfortunately, as other pointed out, it slows down combat a lot. In our case, we dropped it quickly, as fights turned out to be way too long.
We made and tested one solution that seems to work without slowing down combat too much. For every 3 DoS attacker scores in melee, enemy has -10 to his Parry/Dodge. It's not an Opposed Test, but it gives some advantage to guys with high WS.

However, while it worked, we kinda forgot about it after 6 sessions or so, and returned to normal system. But I guess we were just too used to it after playing it for way to long.

I'm failing to understand how an opposed dodge/parry would slow down combat compared to normal dodge/parry. Both parties are already rolling to attack and defend.

Normal scenario :

Attacker (WS 70) rolls to hit, gets 30. Successful hit.

Defender (WS 50) rolls to parry, gets 40. Successful parry.

Defender parried. No damage.

Required rolls to determine outcome: 2.

Opposed scenario :

Attacker (WS 70) rolls to hit, gets 30. Successful hit.

Defender (WS 50) rolls to parry, gets 40. Successful parry.

Attacker got 4 DoS vs 1 DoS, so defender fails opposed test. Roll damage.

Required rolls to determine outcome: 2.

Apart from having to now roll damage for a successful attack (which in the long run will speed up combat) there are no extra rolls required. Determining DoS and comparing them is trivial and shouldn't slow down the process more than a couple of seconds per attack. Am I missing something here? Where does the terribly increased slowness come from?