I realized I haven't posted a whole heck of a lot about Dominions here. Since I got sucked back in recently, originally trying to look something up, I figured I mays as well in the hope one of you join me for a game.
At it's most basic, Dominions is a 4x in a fantasy setting. However, it plays, not through impressive graphics, but through a very well thought out D&D ish system.
Your goal in Dominions is to become THE GOD. Whereas, you start as merely the god of a nation.
Your first choice when starting a game is to find a map, either premade or random, then to determine an age:
Early age tends to have more magic income and stronger mages.
Late Age tends to have weak mages, less magic and stronger troops.
Middle is self explainatory.
Each age has a list of nations to choose from, and for the large part, each nation is unique, with a fairly defined general strategy.
Here we see a Late Age Asphodel description.

Told up front some history and info, we have wild men and a nation that is slowly dying but the forest is reanimating their corpses to fight against those destroying the forests.
This tells us we have a LOT of free fodder for our armies, and need to play a more aggressive early game before our own dominion kills everyone.
Once you have chosen a nation, you come to THE MOST IMPORTANT PART OF SETTING UP A GAME.
You design your god.
From picking a form to magic, to scales.
The dragon form here would make early expansion easy, with his impressive HP, stats, fire breath and natural fear effect, independent armies melt or flee swiftly allowing you to expand single handedly. However, your pretty much stuck with fire magic, new paths being expensive, you're not a great commander later in the game and your dominion is rather weak.

Contrasting with the Lord of the Wild here, who is much less impressive stat wise, would be suicide to try to attack any independent armies solo, but comes with nature/blood standard and is more likely to diversify with cheaper buy in costs, higher dominion, and great leadership qualities to put him at the head of an army later in the game.

After choosing a form, you can alter your magic abilities, with anything over 4 in a path giving specific bonuses to your sacred troops and anything over 8 adding a more powerful secondary effect. Entire strategies can be based on those bonuses. From flaming weapons on a fire bless to reciprocated damage on a blood bless to regenerating HP on a nature.
After magic comes something a little more nebulous in the Dominion and scales.
Dominion is basically a rating of how fanatical your followers believe in you. A stronger dominion will help you push back other faiths. Dominion ALSO acts to passively apply your scales to provinces.
Scales are best thought of on this board as the social engineering of AC. Order vs Turmoil. Growth Vs Death. Hot vs Cold climate. Production vs Sloth. Magic vs Drain. Luck vs Misfortune.
You pick these at the START of the game. Bonuses cost points, maluses refund them. Your dominion then attempts to apply these to provinces as it spreads. There are a few and far between ways to alter this AFTER the game has started. Some nations have different strengths to allow them to absorb "bad" scales easily. Maybe your mages are natural fortune tellers, foresee and prevent disasters. Thus, turmoil might be an acceptable gamble to pay for more production for heavily armed troops, etc.
Form, scales, dominion, and magic all are balance in a set number of points you can spend on your god. You can gain a few more by choosing to have your god asleep or imprisoned (meaning you won't get to have them for ~10 to ~30 turns, respectively) If you absolutely NEED a few more points. One thing I will note, you are much better off choosing to be strong at one area/purpose than to be ok at a lot.
Here is the eventual god I made for Asphodel above's magic/scales.
Magic paths: earth, because Asphodel natively lacks it, and the earth 4 blessing allows my mages to cast more spells in battle. Astral 3 to allow my rock to become the ultimate magic site searcher and teleport around the map (since he can't walk), Nature 3 for specific spells I like.
Scales wise, I took Turmoil 3 to pay for the Production 3. Turmoil makes events more likely and causes unrest in provinces. Heat 2 helps pay for the rest of the scales. Growth 3 NORMALLY would means more population=gold, but for Asphodel it means more walking dead vines. Luck 1 to help make sure those events from turmoil are GOOD ones. And Magic 3 to help me research up the magic trees quickly. (It's really not a very good combo, but I was messing around trying to take it easy on a newer player at the time.)

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Economy:
As with all 4X games, economy plays a key role in Dominions.
UNLIKE most 4X games, there's not a lot of buildings and upgrades to go about.
Cash: You get cash from taxes, based on population. You have to have a line of territory to a castle/fort to collect (OR special units for a few nations that are tax collectors) These taxes are modified by your castle's admin level and distance from and all sorts of fun behind the scenes stuff I don't have a full understanding of. Basically, more people, more money. Some spells will increase/decrease that population and thus the money.
You need cash to hire units, build castles/temples/labs/improvements, hire mercs, and pay upkeep for your army.
Resources: Each province produces production based on terrain, magic sites, and population. This is needed to hire new units, with heavier equipped units costing more. The base resource cost of your troops determines the upkeep cost as well.
Supplies: You have to FEED the army. Terrain plays the biggest modifier in supply. If your army is in a province where there is little to no supply, you better have brought some with you, have units with the corresponding terrain survival, or you may starve.
Gems: The currency of Magic. Most magics cost gems. (some evocations in battle are free, but otherwise, pay up) Gems come from magical sites on provinces that you have to locate by searching for with the appropriate mage or spell.
Castles/Forts: Building a castle or fort has the largest impact on resources and supplies. They will gather from the surrounding lands, taking from those lands and boosting them in the castle's province according to the administration level of the castle. New to Dominions 4, you can build upgrades to the castle to improve that admin level as well.
Spamming Castles/Forts in every province causes them to fight one another for resources for a slightly improved overall gold output. Generally, it's not worth it.
Depending on your position and needs, you might value that province with 30k people for more gold, or that mountain pass with 300 base resources for a troop factory, both in terms of expansion and where to build your next fort.
(busy, more later)