So I'm playing through on hard and the cell, creature and tribal phases don't offer any huge resistance. For whatever reason though I've hit a wall in the civilisation phase - I can barely take a single city before I get pulverised by another nation(s), typically by boat. My strategy has been to spam vehicles to quickly the nearest city and by that time I've got 2 spice mines and a decent income. After that though it tends to go down the pan as every other nation wants to kill me for having too much military might, or in the case of my herbivores they don't take too kindly to religious types.

Any recommendations for tactics or vehicle choice? Spamming cars and boats seems to be the general consensus. Mine focus on health then power then speed.

"So I'm playing through on hard and the cell, creature and tribal phases don't offer any huge resistance. For whatever reason though I've hit a wall in the civilisation phase - I can barely take a single city before I get pulverised by another nation(s), typically by boat. My strategy has been to spam vehicles to quickly the nearest city and by that time I've got 2 spice mines and a decent income. After that though it tends to go down the pan as every other nation wants to kill me for having too much military might, or in the case of my herbivores they don't take too kindly to religious types.

Any recommendations for tactics or vehicle choice? Spamming cars and boats seems to be the general consensus. Mine focus on health then power then speed."

I found the easiest way was to only make a few vehicles, take as many spice nodes as possible then try to get at least one fellow nation as an ally. Use that ally to take the rest of the continent, then stab the bastard in the back. By that point you should have a whole piece of land to yourself which will help with money and defense for the rest of the stage.

Ignore the spice mines man, empty your city out and completely abuse the factories.  Every factory thats next to either the town hall or a house gives you an extra 400 gold a minute.  If you really push it you can crank out 6 vehicles before anybody manges to attack you and then rush the closest one, rinse and repeat the factory farming.  Unfortunately this does leave you way open to religious units tho so make sure you have a good defense or turrets and some land vehicles.  Also forget the air units, they die way too fast to justify them, with the military route at least.

OR...you could try allying yourself with some nations, gaining the profits of it and then turning on them. Think outside the tank rush box dude..

Turrets, Turrets, Turrets!  They are the key if you want a military victory.  Quickly pump out 5-6 land vehicles and cap as many spice mines as you can.  Then bring them back to your captial and start building up turrets.  A captial city with 8 turrets will be very tough nut to crack, even on hard.  Generally, a combined force of 4-5 ships and a full array of turrets is enough to keep your capital safe while you gobble up your weaker neighbors.

Be aware that this does mean you start off lagging behind the other civs. This is actually an advantage as the AI spreads is forces too thin and has trouble responding to a focused all out attack on their weaker cities.  So in closing, build lots of turrets and take your time.  Slow and steady wins this phase on hard.