The weak start

one thing you can try is to use some scouts to 'walk' the deadly armies away from their spots.  you may need to sacrifice a scout to get the monsters to move initially, but once they're moving they'll follow a scout far away from your city and a hero can sneak in and take out their lair.

Ive been playing on insane/insane

as of now I'm just starting with pioneer and making a new game if I'm trapped

 

even if you can expand, that city has a chance of being destroyed as some uber unit you can't possibly kill decides to wander into your lands

 

im still new to the game so don't take this as strategy advice lol

There are a couple of things you could do:

 

First: Certain combinations can take out dangerous enemies much more quicker than others, which greatly reduces the odds of being in some way trapped. IIRC, Gilden and Krax also get Spearmen with traits,

 

On very high world difficulty levels, custom Ghilden bloods factions (due to guarded strike) are quite good with this, as are souvereigns with beastlord.

Kraxis blood is also solid for such situations.

If you are an Empire, get some death magic for blindness which helps a ton with singular tough encounters.

 

For fighting the AI, if you have crystal, warg mages (1 warg bought from the AI only costs 6 gold usually, 20 Wargs go a long way, and only cost 120 gold) are reachable techwise, and will basically ignore the enourmous AI defence boni the AI gets from researching refined defence insanely quickly.

My army in a current insane insane game consists for my defender souvereign that is basically tanking the enemy army, an Ophidian (I do get hit by strategic AI spells, so I guess this magic immunity does not quite work), and a bunch of cold mages without wargs because the AI went for me too quick.

 

You will likely use the majority of your mana to delay the AI armies on the strategic map (or cloudwalk, or tornado) anyway, so the gilden spellcasting malus does not matter much. 

Golems (if well designed) also have more niche uses on insane than they would have under normal difficulties.

I've completed a game on Expert where I had one city early, and if I remember correctly I was able to build one more after a few dozen turns, but then I ran into an AI who was way more advanced than I was, and there was no way to go past him. My capital city was quite a good one, and I was just about able to hang in there. I was in a barren peninsula, but I could only be attacked from one direction, and I did at least have access to wargs, crystal and gold mines. I'd agree that warg mages are handy. Eventually my neighbour declared war on me, and I was able to kill his initial stack while defending my capital, although I think I needed to reload a save game. I was then able to build up another stack to chase off his forces and go on the attack. I had to wait outside his capital city until he decided to send his sovereign for a wander, at which point I was able to take it.

My first game on Ridiculous there was no second settlement site to be seen; I did eventually find a usable one but the AI got to it before me. I paid tribute, then attacked the AI to get that city. The AI could probably have retaken the city, but instead sent its stack to take my capital! I died. Chalk one up for the AI.

If you have a terrible starting position it may well not be recoverable on higher difficulty levels. Personally I would play through it as quickly as possible until you either have a viable kingdom or you've lost. I don't believe in reloading the start, playing a really tough position may teach you new strategies that you'd never consider using if everything was going well. But on the other hand I don't see an awful lot of point spending hours on a game where you're probably going to lose even if you agonise over every single move.

with default monster density, it's usually not so bad. sometimes you have to wipe out a lair or two early on to settle a few more cities. not a big deal. can be crippling with dense monsters, though. if you have to remove half a dozen lairs to even get out of the valley you started in, the game can actually be lost before it really started. probably won't catch up to AI factions that had a better starting position.

Don't forget Magnar/the Quendar.  You can use slaves to build up huge armies quickly that can do a lot of damage at  the cost of most of the slaves (death lash and cull the weak).  Magnar players can use this strategy to kill much more powerful monsters much sooner than other races.  You can farm bandits and such to improve the size of your capital fast (Quendar turn defeated human opponents into slave pop at their capital) and get one very high level city that can at least somewhat mitigate not having many others.  You could make your sov a mage and use the high mana base from your huge conclave city to spam spells and take out more powerful stacks that way.  You could also field very large armies which, while somewhat weak due to being mainly comprised of slaves, would at least not take upkeep that you can't afford to pay.

It's an unconventional strategy but I'd say it would be your best shot at winning in such a situation.  

Having only 1 city at higher difficulty levels isn't bad, I do that intentionally at Insane difficulty.  Defending a city at that difficulty level, even against just mobs, requires a decent army.  Getting one decent army takes time, and expecting it to also defend a second/third city is extremely risky (unless your second/third cities were close enough for 1 army to defend both/all -- but that means you have a great start, and the topic of this thread is bad starts, so never mind...).

Now, if the area around your capital is bad, and you're boxed in, then at higher levels you're screwed.

If, on the other hand, you have 1 decent city site and are boxed in, you can concentrate on that city (make it a fortress, with all the possible unit-upgrade buildings/city spells/etc., research leather and a few unit upgrade techs), then with a full army or 3 of maxed-out units, bust out, and then add cities.  At Insane/insane I don't settle a second city for quite a while even if there are nearby good city sites, as defending them early on is too chancy.  Plus the longer I can delay meeting the AI sovs, the longer I have to build up before they can declare on me or I have to pay tribute.

Interesting couple of posts. I'm not convinced of the viability of a one city strategy on higher levels, but respect to Nick-Danger if you've made it work. I don't see how you can get sufficient research and gold from one fortress to get a decent army, but maybe if you have access to resources which compensate.

I agree though that the crucial thing is how long before you meet the AI. If you meet an AI early who is more powerful than you and the AI grabs all the city sites around, it's tough. I guess if you have a good enough first city I can see that with time you might be able to build up a decent enough stack that you can take the AI on, especially if you have access to cheap troops (which several sovereigns do in some form or another). But if the AI declares war on you, and/ or the AI has a big enough research lead, it's going to be seriously hard work. Killing high attack and defence AI troops when you have leather and basic weapons is a struggle.

The couple of times I've been boxed in on higher difficulty levels, it was a struggle to even get a good enough stack to complete quests and kill monsters who were sitting on top of resources. Maybe one city can be made to work, but one city and not enough resources is a certain fail. I might give the "one decent fortress" strategy a go some time though.

My apologies, it appears I was unclear.  The '1 city' is just for the start.  I don't create the second city until I can guarantee both cities can be defended from local/wandering mobs.  This means I delay the second/subsequent cities longer than I normally would (for many turns if necessary), instead building a couple of sufficient armies.

Creating cities before they can all be properly defended has been found to be too risky -- trying to guess which city will be targeted next and getting an army there in time is too chancy.  I've found a more conservative approach is better for my play style and fun.

Once I can defend subsequent cities, I expand as fast as reasonably possible.  At about a half-dozen cities the unhappiness penalty becomes problematic, and I'll then focus on outposts to grab resources, while trying to bring down unhappiness to then add more cities.

Generally, I try to get champs ASAP and give each a full army, using my sov's army as the 'go out and conquer' force, with the weakest/newest doing guard duty at the opposite end of my lands.

Sorry for being unclear.

Back in FE I had a great start one time, and tried a 3-city challenge (similar to Civ4's 1 city challenge) on Insane/Insane, where I had 1 fortress, 1 town, and 1 conclave.  Never finished it (game was patched and things changed), but it was interesting.  Will have to try it again with LH.

To better explain (and so I can 'consolidate' my thinking on this), here's examples from my current insane/insane game, just before I started my second city. Note, this isn't a 'bad start' as you're asking about, it's just an example of putting off a second city and building up the capital, to be able to defend against insane/insane.  The strategy here may be useful in some 'bad start' games where you have a decent starting location but are 'boxed' in, helping you to break out.  Against a very strong AI boxing you in at high difficulty levels I don't think this (or anything else, really) can help, as the AI at high difficulty levels researches/builds/etc. too fast.

It's currently season 72, I only have 1 city, and am ready to finally build city #2.

My capital, a 3/3/3 fortress (with scrying pool so 4 essence):

Note I have 2 unit-enhancing city spells, that's all I have at this time.  I added more as I got them.  I put these 2 unit-enhancing spells off until just before the units were created to get the most out of propaganda and inspiration (that I had been using), then exchanged them for the unit-enhancing spells.

I had a very nice second city location available, but it was judged too far to defend it and the capital at the time, especially as I didn't have economics (for its road between cities) at the time:

Here's a zoomed-out view, outpost to the south, capital in the middle, and second city site to the upper right:

Instead of founding a second city, I built this outpost south of my capital:

Gold mine, earth shard, clay pit.  It was a bit of a chance, but deemed much less risky than the second city site, as the outpost is on a 'dead end' peninsula I had cleared so was fairly safe from wandering mobs and AI.  The second city site has open, unexplored land to its east, north, and west -- too many unknowns.

Here's my 'finished' army, with which I felt I could finally sufficiently defend 2 cities:

Sov, lvl 3 warrior champ, Brothers Sparus (the quest guys), and 3 spear maidens.  I had researched economics by this time so would have a road between the cities, so 1 good stack should be able to defend both cities (or so I hoped).  I also could relatively quickly start/complete a second/third army to defend a third/subsequent cities.

I guess the Cliff's Notes version of all this is that sometimes slow is fast, and fast is slow -- Delay subsequent cities then break out fast, instead of making a number of cities that you can't defend against bad luck and wandering mobs/AI.