I’m doing the solo Red Crypt adventure. It provides basic rules for rats and bats, and also limits them to 2 per hex. It wasn’t until after my first rat encounter that I looked back at the ITL entry for them, even though I had some uncertainty when running the encounter.
Things that stand out from those rules:
- Rats must be in your hex to attack you.
- You can use a 50/50 die roll to determine if they hit you. (Note this is only a recommendation for speed; it’s not the “standard” as someone stated up thread. You could use regular rolls and even score crits for the rats.)
- Damage scored by the rats is cumulative within a round, and can overcome armor this way (a point missed by a couple posters.)
The thing that strikes me about points 1 and 2 is there is no mention of the rats in your hex being considered to be in HTH. Otherwise they’d have a 14 adjDex for the rear hex bonus HTH gives you, and you couldn’t use the 50/50 roll.
From a logical perspective, they’d have to be in HTH, as they’d need to be literally on you to attack, unless you’re just sticking out your fingers for them to bite. Either way, the PC is
not in HTH, per the rules for smaller creatures engaging large figures in HTH per ITL pg 117.
So I guess my final ruling would be creatures so small as to be unable to attack from adjacent hexes simply use the regular rules for attacks, and do not get any of the advantages or disadvantages of the HTH rules.
As far as the number that can attack, I’d say it’s a factor of the creatures size compared to the target. A third the size? 3 can attack the target. A quarter? Four. And so on, with an upper limit of 10, just for manageability’s sake.
Alternatively, creatures a tenth or less in size I’d consider creating some rules for swarms, treating them as a single creature, as others have suggested here.