So people have been grumbling about 5e.
(tl,dr: advantage is great! but it has consequences - the players engage less. A proposal to fix it)
I think 5e is a good game. But like all versions of D&D, it's not perfect. Compromises had to be made (I consider it "medium crunch" and I am happy with the level of complexity, but for some it's too complex, for others not enough). Some new rules had unintended consequences - the "sort rest classes vs long rest classes" balance depends on the pacing of the game, which is strange. There is no longer a "magical item market" where you could customize your magical gear - some see this as a good thing (I do!) and some see it as bad. Some say that the game is too easy, that the PCs are too tough (a valid criticism I think).
However, the advantage/disadvantage system was almost universally praised. And it is good! It was a bit... much... at times in the older editions.
This is an example from the PF game (the kingmaker AP where I play an alchemist)
"My starting to hit number is +9, but there are modifiers. I have drunk the mutagen, which gives me +4 to dex, which means +2 to hit. I've also cast reduce, which increases my attack by 1 and gives me 2 more dex so another +1. The foe is 25 feet away so point-blank shot kicks in, giving me another +1, BUT there is a -2 range penalty. The bard is signing that's +5 right? (our bards is *awesome) - nope the bard is more than 30 feet away from me, reducing the bonus to +3. I'm also firing into melee (-4) and there is some cover (-2) so that's not great... but wait I'm hasted by the sorcerer, so I get another +1! So now it 9 +4 +1 +1 +1 -2 +3 -4 -2 + 1= +12 (... I think)... vs touch attack armor"
And this will change every round - did I take just take dex damage, or been hit by a debuff? did range changes, is cover less (or more), did a buffing spell expire, the bard stopped signing, etc etc etc."
Advantage sweeps almost all of this away. With very few exception like cover, in most situations you have advantage (roll twice take the best), normal chances of success, or disadvantage (roll twice take the worse). This ended the constant re-calculations of bonuses changing from round to round. It made the game faster and easier.
But some of the discontent about 5e was more... nebulous. Some blamed the "Mercer Effect". Others that the game didn't "feel" right.
Recently, I saw this video about 5e being like super-heroes and how the character's power all came from their sheet and that the rewards of engaging with the world were less - you could just use your "own" power to win. Now this video wasn't quite 100% right. you still need the other PCs IMO. And it didn't quite explain why you didn't need to "engage" anymore.
But that video made me realize what the issue is - it's advantage! Once you have advantage, getting more help doesn't matter.
You don't need to find the higher grounds. You don't need to flank the giant. Just get advantage by doing *one* thing and you're good. And a lot of classes have ways to easily give themselves or others advantage. So you don't need to engage with the world as much! Just show up, and get ready to rumble!
So... how do we fix this?
First, Advantage is not a 2nd d20 roll. It's a +1d6 bonus. This is roughly the same as advantage (advantage is equivalent to +5 *if* you have 50% chance of hitting. If your chances are very low or very high, the impact is less. So +1d6 is roughly equivalent).
Second advantages stack - you could get more than a d6. But for things not to get completely crazy, (good or bad: disadvantage stacks too!), the extra D6 don't add, it's a "take the highest roll". So if you have advantage from 3 sources, one source of disadvantage, roll the 1d6 twice, take the best, and add this to your 1d20 roll. So if you have a *lot* of advantages, the bonus will approach +6
I *think* this might encourage re-engagement with the world and terrain, but without the excessive complexity of pathfinder/3.x....
EDIT: It's been pointed out to me by a number of people that this 1d6 solution can be found in the game Shadow of the Demon Lord. Given the amount of time I've spent on the OSR discord, it's quite possible that I saw that there, "forgot" and then half-remembered it when I was looking for a solution. I certainly don't want to take credit for something someone else thought of first!
I think that while the solution (original or not) is important, identifying the problem is my main "original" contribution. I also note that the solution would need to be play tested, as it has a major impact on the critical hit system, and a few feats.
Another thought: would this stack with bless or guidance? Yes, it would, same way advantage stacks with guidance/bless, and this should go for other "bonus dice" that 5e can grant.