... stealthing... taking out the potential runners... surprise... enticing monsters to come to us... all kinds of tactics we now have to think about again.
I've been playing RPGs for a long time, I'm very familiar with all of those, we use them extensively in our normal games. We are obsessive about not letting anything get away, our normal GM can be a real RBDM about how badly they punish the players for letting even the most trivial enemy escape, to the point where we refuse to even take prisoners since the few times we did they proceeded to teleport away to escape and completely screw us over. We stealth, we kite, we divide and conquer, we combine fire, we use and abuse terrain, we use surprise (stealth, disguises, unusual approach directions, etc.), we scrap and scrape for any advantages we can get. Our normal game is 4e, and our "adventure day" is typically 8-12 encounters (I think we have gone as high as 15 once) against almost exclusively above level encounters.
I can't conceive of any of these helping in the playtest scenario against the kobolds. We were operating on the GM's advice to go to cave "A" because they were in ascending of danger, and "A" would be the safest place for us to start as we learned DDN. If he was right and "A" was the least challenging, then we shouldn't have been playing as heroes, we should have been playing as cowards that just picked off a kobold or three at range at a time and then ran away, repeating over the course of several weeks until we had enough experience to level up, at which point we could be brave and try to pick off 2-4 at a time instead.
Stealth - The only party member with a reasonable chance to stealth had a hard time finding their own head with both hands in the kobold cave. The thief doesn't get their skill mastery on perception, since they aren't trained in it, so the scout of the party is operating with a penalty to their perception. The thief also can't see in the dark, so they can't scout into the cave at all (unless they carry a light, which totally defeats any stealth attempt). The thief is also tied for the slowest speed and lowest hit points and has a mediocre AC, so good luck running away once you eventually get spotted by a tribe that all carry ranged weapons and gets automatic advantage for outnumbering the lone character (even the base kobolds have better than 50/50 odds of hitting the thief). The dwarf fighter is the only party member trained in perception, but he has disadvantage on all stealth checks due to armor.
Taking out runners - There just aren't enough actions available to the party. The outside group was 8 kobolds, if every member of the party hit and took out their target (unlikely with them in cover), and the cleric with no ranged attack was close enough to get an attack in, that leaves 3 runners. The next group had 6 kobolds, so at least one would survive to run. In both cases, every one of the enemies was easily within a hustle of terrain that would completely block the PC's line of sight on their way to get the reinforcements, and the same terrain made it impossible for the PCs to reestablish line of sight and still be able to attack to pick off the runners.
Drawing them out - Why would they bother to come to us? They outnumber us, live in a prepared defensive complex, have ranged attacks, and since we need a light source it is easy for them to spot us, plus they are better off staying out of our light to avoid disadvantage and where two of the party members can't see them.
Surprise - Once again, since some members of the party need light, surprise isn't going to happen. Well, I guess it could, we would just need to pick the two players we like least, stick them with the thief and cleric of pelor, and tell them to go sit in the corner while the rest of us play the adventure with the characters that can see in the dark. Even if we could get surprise, because surprise is now just an initiative penalty, the enemies can still run during the first round of combat. In fact, if we get surprise they are probably more likely to run since they would have seen how much the party could do with a full round of actions before their initiative comes up.
I expected the Caves of Chaos to be something manageable for the characters that were provided with the adventure, not a Tomb of Horrors style deathtrap. Not counting the kobolds outside, the party can very easily end up facing over 70 enemies within 30' of the entrance, all of which get advantage for some flavor of outnumbering you. I think I would have been happier if the GM had just ruled that an asteroid fell out of orbit and flattened the party, at least that would have been quicker than waiting for the DM to roll attacks twice (advantage) for dozens of enemies that poured on top of us as soon as we walked in the door.
As is in the DDN rules, if you encounter a group of enemies that outnumber you, unless they have to run for multiple rounds in your line of sight to get to their reinforcements, there is no way I have found to stop them, at which point you get the joy of fighting every enemy in the entire complex at the site of the first encounter.