I'm thinking of adding exploding damage dice to my game. It's in a lot of different games, and I think it is pretty cool nifty little tactile reward for players.
So if a 5th level Rogue hits with a shortsword, he would roll 4d6.
so if he rolls 4,4,2,6. He gets to roll another d6 because of the one high roll of 6. Let's say he rolls another 6, he would roll again until he rolls a 1-5. and that would be the final damage score. So let's say he rolls a 5 next. so that would be
4,4,2,6,6,5 for damage.
or 27 points of damage from his attack.
With the same scenario if the Rogue hits with a critical, then he is rolling 8d6. 
I don't think it would break the game, but would be a cool house rule to add for players.
What do you think?
I personally love tactile mechanics - some of my favorite games or alternate rules have played with these. (In Magic terms, these are some of the few rules that awaken my Timmy side.) However, blanket-allowing exploding dice (especially if they're cascade-exploding, where a reroll can itself explode) gets a bit over the top. Especially because the raw numbers in 5e aren't as high as explosions can usually reach, and explosions take more time and rolls to resolve (5e tries to minimize these). Explosions are also a little swingy, which biases things against the players if they're present very often.
Personally, I'd pick a small number of places and use it there. Actually, the rogue is a good example: maybe Assassinate doesn't auto-crit, but rather makes all the damage dice explode. (If this potentially gets too strong, it can easily be such that only the weapon dice explode, or that the weapon dice have a cascade while everything else only explodes once). As a side effect, this actually encourages assassins to use daggers (since d4s are the most likely to explode) instead of rapiers (the traditional swashbuckler weapon), and the fighter/rogue multiclass has reason to consider Champion instead of Battle Master (since Assassinate doesn't autocrit under this system, more dice is not ideal - but the wider threat chance gives you a chance for even more seed dice for the explosions).
As an alternative, you might consider rerolling 1s and 2s, which has the same overall tactile effect as exploding but doesn't actually raise the damage. It's also tailored for rogues: currently, they can't use Great Weapon Fighting (there's no weapon that works for both GWF and Sneak Attack), and d6s roll a 1 or 2 more often than d8s (the die used by paladins, who can reroll it already with GWF). For the record, here's what rerolling 1s and 2s does to Sneak Attack with a dagger and 3d6 or 10d6 Sneak Attack.
I think if you gave exploding damage dice to your players, they'd be a little miffed after the innocent looking plastic cubes blew up in their faces.
Exploding dice have a place in a system designed for them, which D&D isn't by a long shot.
That said, I prefer treating dice after the first as having a -1 to their result. For example, a d6 rolling a 6 would then be 1d6-1 for values of 0-5 rather than 1-6, which allows rolling of all values on a die rather than every 6 rolled on a d6 actually being at least 7.
I think you will find that it meses up the balance a bit. It doe smake daggers and slings better. a 1d4 weapon has a 25% chance of exploding. It will make 8d8 fireballs/lightning bolts, etc more powerful. And assuming you apply it to the monsters as well 9 as is only fair - your PCs will be going down unexpectedly (mainly a lower levels) from lucy monster damage rolls. If you use monster averages and don't roll, then your PCs will become more comic book-movie super fantasy heroes. Which will be okay if you want to deal with the headache of planned encouters that end unexpectedly fast from time to time.
Tempest_Stormwind wrote: