Thus any realism added by my proposed features is just a nice side effect, main task was to improve playability or fix some issues.
For example, in civ1 knights were important, but since elephants were introduced, both chariots and knights are skipped,elephants and gunpowder are win-win path of progression. There is also some annoyance with infantry tiers, you start with units specialized for attack/defence, than here goes 3/3 musketeers, and next there is no defence infantry, only attack one. Other inadequacy is whole end-game tech tree - it looks like Microprose urged Sid to finish his project, what for is Fusion Power? On the other hand, quarter century elapsed, it is worth to mention new futuristic ideas.
I tried to bring some balance into the game, thus key technologies such gunpowder or nuclear fision, are harder obtainable, I added also more gradation into units and tech tree.
Because I'm lazy with painting, I'm grateful for all needed graphics which I found on this forum and shamelessly introduced in my project, I reused also some arts from other famous Microprose GPL-based clone, OpenTTD, credits included in .spec files.
Firstly, I would like to introduce shortly new features. I will expand this post later with more detailed descriptions.
New governments:

Increased money income from sea, albeit decreased inland productivity, no distane production waste, small empire size, veteran status for new ships.

No base production waste, 3 free upkeep and 3 martial law, no civil war if no statue liberty build by player, medium empire size, elite paratroopers
New buildings:

25% city production bonus, trade points from coal mines, obsoleted by Corporation

50% tile production bonus from forest, trade pts from silk, river req., obsoleted by Plastics

50% tile production bonus from coal/iron mines, trade pts from iron mine, high pollution, conflicting with Research Lab

50% tile production bonus from mountain mines, trade pts from coal mine, high pollution, conflicting with Research Lab

Necessary to gain additional bonuses from Railroad tiles. Default shield bonus from railroad decreased to 25%, but railroad together with Railway Station yield additional output from some special resources or from mines (together with Steel Mill or Cement Plant). Instant hp regen of train class units

100% tile production bonus from desert oil rigs, req. for oil shore platform, trade pts from oil rigs on oil field

plague probability 10% less

plague probability 10% less, req. for city size above 32
New industries increase production from certain resources, and can have revenue (usually equal upkeep costs, so net value is 0),
for example Steel Mill upkeep is 4, but if there is iron resource with mine, revenue is also 4 (thus upkeep is free). Power plant have 2 pots trade from each coal mine.
Other changes: supermarket is somewhat detached from farmlands, farmlands need Chemical Synthesis advance to allow second irrigation and have (smaller) bonus without supermarket, but supermarket (Refrigeration req.) remove food waste from tiles with farmland.
TODO list:
[*] cement plant, increased shield production from mountains mines;
[*] fusion reactor - no idea how it should look like, it is nice toroid but inside building...
New small or great wonders:

1 immediate tech and plague probability 10% less, together with all water/sewage amenities, Hospital and Cancer Cure, total protection is 95%

Increased min size not causing unhappiness, but penalty on rich tiles trade (gold gives 5, not 6). This small wonder is required for Women's Suffrage.

1 new tech, 4 bulbs for city, 50% for any research lab

Map revealed

2 new techs, convenient method to achieve Great Unification Theory, which is very expensive

Required to make Spaceship Structurals

Effects similar to Shakespeare's Theater (which is obsoleted by Nanotechnology). Unlike other wonders, Hollywood have expensive upkeep.

Faster heal of infantry units.

Random unit upgrade (like Leonardo Workshop). Prerequisite to Internet wonder.
New units (amplio/trident images, X=lack of image):






























































































(u): unique units
Other changes - Airplanes movement was changed, increased amount of fuel - fighter have 2 turns between landings, bomber 3, but fighter stops after attack. Bomber can carry bombs.
New unit system, five classes of infantry: attack one (Legions, Arquebusiers, Grenadiers, Stormtroopers, Marines, Supersoldiers), defend one (Phalanx, Pikemen, Musketeers, Riflemen, Infantry, Modern Rangers), recon/hitman (Archers, Arbalests, Marksman, Sniper), pacemakers (Warriors, Halberdiers, Riot Police), spec-ops (Vikings, Corsairs, Navy Seals).
River movement bonus decreased to x2 and applied only to workers/engineers, raft, settlers, merchants etc small units.
Engineers can carry 1 cargo, thus can be used as temporary bridge for big land units.
Trireme class expanded to: Trireme, Galley, Steam Barge, Diesel Barge, Monitor, Patrol Boat, Cog and Steam Paddler added to merchant ship tier.
Artillery turrets and torpedo added as was described here: viewtopic.php?f=11&t=90430
Todo list:
[* three branches of infantry, for defend, attack and assault - the latter one (archers, arbalist, marksman, sniper) with Bombard flag;
[*] pictures for trident tileset;
[*] include idea with rivers as obstacle and river boats viewtopic.php?f=13&t=90354 ;
[*] change upkeep parameters: each unit need 2 types of upkeep, some governments have one type of upkeep free;
[*] two kind of artillery: direct fire (catapult - these often were giant crossbows, cannons, artillery, mobile artillery) and indirect fire, with Bombardment flag
- trebuchet, mortar, howitzer, mobile howitzer) - basically Corbeau idea but with revised parameters (currently tested with AI).
Issue: AI have no idea how to use units with Bombarder flag.
[*] Turrets for ship customisation;
[*] Bombs for aircraft;
[*] New governments: ancient republic, ancient democracy (intermediate ones), and republic/democracy shifted to more advanced achievements.
Tech tree picture is here:

Some techs have root_req flag - it is not such restrictive like in case of experimental ruleset, only few key technologies have it, and usually root requirement is deeper than directly required advances.
For example, Republic require Literacy and Currency, but you cannot acquire it, if you don't know Code of Laws already. Gunpowder need Alchemy and Invention, but require also Iron Working and its prerequisites, etc.
TODO: future goal - possibly merge this project with Neolithic tree?
+ idea with special traits for Asian civilisations (dead end branch of tech tree, but supreme units and some wonders)
Download here: http://149.156.194.203/~mczapkie/fc/adv ... anced2.zip
Note: Use advamplio tileset to see new images.
There is also advtrident tileset supplied.