Exploding Crits? I don't think I've heard about that before.
Original was Exploding Dice. Works like this:
Say you have d10s. Every 10 you roll means you roll another dice and add the results of that as well. That rule applies to dice produced from 10s too. So theoretically, you could have arbitrarily large results on any given roll. That can mean the lvl 1 peasant child just parried the Dark Lord and lobed off his head. Whether that's awesome or stupid depends on your taste and what your trying to get out of the game.
A variant popular to quests is exploding crits. If you roll over 100
after adding bonuses, you roll another dice. Repeat as needed. That can be awesome, though it can also very easily lead to suspicion that the GM isn't rolling properly if it happens too often. Still, you can get some cool moments out of it. Corporation for Occult Research and Extermination is an example for a quest that uses the mechanic and, IMHO, exhibits both the advantages and disadvantages. And there's a quest on QQ about Kakashi's twin brother OC called Karasu that goes further with it than any I've seen, and rolling mutliple dice through that mechanic became standard, with bonuses to later rolls specifically.
A few notes: First, exploding crits make bonuses on your rolls more important. Every additional +1 means not only a better base roll, but also a better chance for more dice. Roughly, every +1 is actually worth on average a +1.5, since you have +1% chance of another 50 (expectation value of a d100).
Second, a lot of quests that use that mechanic also allow users to boost rolls by writing omakes. There's synergy there, because getting another dice feels like a big reward for the effort of writing, and the spectacle that's encouraged by the exploding crits mechanic also fits the tone that's encouraged by people writing lots of omakes to make their side more awesome. The excuse of randomness plus the investment from directly shaping parts of the narrative (by adding a bonus in the main story
and writing an omake) also gives you a lot more leeway in writing stuff that would otherwise be a horrible mary-sue. And to be clear: That's not a bad thing. I enjoy that sort of thing too when I'm in the mood, and it takes it's on type of skill. It's an observation on how the type of stories you can tell differs with the medium, and how both (seeming) randomness and listener involvement shift things.
