I tried the no-missiles challenge a few times, but found it impossible because 1) the orcs would sometimes arrive before I had more than my 7 starter dwarves, 2) if the orcs themselves came with missile weapons, casualties were usually high enough to start a no-migration spiral and 3) I just generally didn't have enough time to armor my dwarves, and without armor I lost too many recruits to sparring injuries. I think that the blackmetal weapons I was giving them might have been a bit too rough for the barracks floor, but I've yet to find a map with lots of sub100% metal and all of the micromanaging via forbid is really clumsy.
I abandoned my most recent Dig Deeper fortress because I overdid it defensively and it ceased to be challenging. All it took was [C]onstructions and replacing external doors with [l]inked [f]loodgates, and I was able to destroy sieges of 70+ orcs with no more than 6 marksdwarves. I let the corpses turn to bones, and voila! Enough ammunition to keep the cycle going indefinitely. If they showed up with archers I would usually lose the squad of 6, but it was so easy to just recruit more and send them out that I was still winning wars of attrition.
If there was a way to hard-code "orcs don't show up until at least the second year" I might try the no-missiles challenge again, but the only way to tune them is by using the [PROGRESS_TRIGGER*] tokens, which by definition means working with a grey area. I play at a fairly low FPS compared to most (35), so it takes a few hours just to reach my first Autumn caravan -- investing those few hours just to find that I get orcs before I get migrants was a waste of my time. The worst part is, there really isn't any way to race it; in order to get earlier/more plentiful migrants I need to aim for as high a production as I can early, but that also hits the very low [PROGRESS_TRIGGER_PRODUCTION] token and means I get even earlier orcs!
I considered deleting all of their [PROGRESS_TRIGGER*] tokens except for population; that seems like a fair compromise. Even with the more plentiful coke, though, it's just so very labor intensive to get a squad of melee dwarves trained and armored without also crippling half of them. It also seems that I'd need to maintain over 50% of my population as military, which is all well and good except for the situations where the loss of a few dwarves starts a migration-dampening spiral which causes more casualties which means less migrants ... and so on.
iow, the orcs are challenging, but the same ol' same ol' tricks are still more than enough to trivialize them. By abusing the immutability of [C]onstructions and [f]loodgates, even the 7 starter dwarves with wood crossbows can defend themselves from almost any siege (opposing archers might be bad news, but the [F]ortification AI is pretty awful so sometimes their archers just stand there getting shot with impunity anyway). Without using those tried-and-true tactics, or other cheese like bridgesploits, the orcs remain challenging ... but possibly a little too much. That's just the nature of the randomness of the game, though, and as long as that randomness is there I'm not going to keep attempting the melee-only challenge; it's just far too likely to result in me having wasted several hours just to get sieged by 16 orcs against 7 recruits.
