I've been playing this from time to time since it came out. Nowdays I find that I return to it for a weekend 1-2 times a year.

What got me hooked is the feeling of the game. The background music, cut scenes and story just works for me and sucks me into the game.
It is quite different compard to modern Civ (4 and 5). Initially the older graphics/sound will hit you but I think that should pass fairly quickly. The long term changes is about game mechanics and balance. I've recently played Civ 5 and find it in some sense 'shallow' compared to SMAC. I think that has to do with the way resources etc affect the dynamics of the game. In modern Civs, I feel the dynamics beneath the user interface are harder to understand and reason about in detail, while in SMAC, many game concepts and calculations are directly documented in the help texts. (Be sure to use 'F1' in the game)
Also, modern Civ games have been balanced to the point where it is hard to stray to far from the way the designers intended the game to be played. Of course there are variations, but mostly within specific winning conditions.
SMAC retains the raw exponential law that allow a small edge in the beginning to grow over time. I think SMAC is more sensitive to mistakes the first period of time compared to modern Civs.
What I really like about SMAC is the depth. Once you get over the initial city building/combat there are a ton to try out in terms of social engineering and the Unit Workshop. Those really set SMAC apart from Civ.
As for difficult, there are easy settings that allow everybody to get into it. You can automate a lot in the game but I do think it require a bit more micro management than modern civs. But not so much to bother me.
Think there are 6 levels available. I find level 3 easy and play on level 4 (librarian). After reading up on strategies on the net, I can now beat it most of the times. I think level 5 and 6 are still out of reach.

I summary, if you want a game that do take some effort to fully understand has a great narrative and general feel to it, I think you should try it. It definetly got that 'only one more turn...' quality to it. One of the few things that can keep me up to 6am nowdays.

/ Mikael R

It doesn't sound too hard then, though the more depth will no doubt be confusing at the start, it would be nice. Something I miss, Civ 5 seems to be more you own the top end resources and there isn't much more to do.
Though I suppose it comes down to the challenge, at the moment I'm playing on what's meant to be hard, but the only thing that is hard about it is the happiness, them attacking is basically a joke. They just launch their army and sit there doing crap all.

Kyrub's patch can significantly improve AI when on Transcend difficulty with aggression enabled.

You can edit the .ini file, set the parameters the way you like. I for myself allways set the technology rate very low (20%) to enjoy every single phase of the game.
Just keep in mind you can't chance the settings of a savegame and have to start a new game.

There is A LOT more going on in Alpha Centauri than in Civilization. It's not that the game itself is more difficult, so much as there are far more things to keep track of. Concepts such as:

1. Limits on expansion set by "Bureaucracy"
2. Effects of "Efficiency" value on your economy between different factions and policies
3. The balance between population growth and staving off Drone Riots
4. The lack of a National Gross Happiness value from Civ, since "Happiness" (Psychology value) is localized by individual bases/cities
5. The incredible significance of winning the race to a Secret Project versus the relatively minor buffs of Civilization's Wonders (except for some things like Civ 2's Great Wall)
6. Mind worms (the "barbarians" of Alpha Centauri) remain a threat as the game progresses; they are at their most threatening in the early game, but they never fade into obscurity like the barbarians of Civ do
7. The need to create forest tiles to reduce Ecological Impact, instead of using them to either build Lumber Mills or raze them to build important things more quickly; versus the need to increase the resource yield of every available tile as much as possible through improvements and terraforming, which often increases Ecological Impact and/or creates man-made climate change
8. AI factions incessantly want you to trade or even give away your research accomplishments, and eventually unally you or go to war with you if you never share them, especially the Believers faction (giving away your research is an important diplomatic choice you will never worry about in Civ)
9. Stacking military units in a single tile, like in Civ 1-4, or placing several individual military units around another nation's borders to scare them like in Civ 5, are possibly two of the worst things you can do in Alpha Centauri; especially when faced by a faction with experienced Probe Teams and lots of spare cash (particularly the Morgans and the Believers)
10. Two of the BIGGEST tactical differences from Civ- your military units don't just attack or trade blows once with the target, the two will always fight to the death upon contact (unless one of them has the ability to move away during a losing battle); and unlike Civ, cities/bases with no military units occupying them have no defense at all, they will be instantly captured if another faction's military unit moves in, or your population will die by at least 1 if a mind worm moves in - significant, because even if war is not declared, faction boundaries do not prevent others from entering them!

This is just a small list of things Alpha Centauri makes the player remember, that for the most part Civilization doesn't trouble you with. (Besides population growth versus happiness, although Civ won't let you Nerve Staple your citizens to force them to work.) The actual AI difficulty depends on whether you implement the unofficial AI patch, and whether you turn on "Spoils of War" (makes military focused factions more powerful than usual) and "Intense Rivalry" (makes diplomacy more difficult than "give me a tribute of money and tech").

All of these things can make the game harder to learn, but the overall difficulty at game start up is more modifiable than Civilization, so you can greatly reduce the need to worry about all of these things.

Stick of Plywood has very neatly summarized everything for you so I won't repeat what he said.

I'll just say that the game has several difficulty settings. You can start at one of the easier ones in the beginning and just increase it from game to game, as you become more experienced. You will get trounced first time you play. Especially if you land near factions like Believers, The Hive or Spartans. I never give in to threats in 4X games. But in SMAC you just have to know when to choose better part of valor and even give up valuable tech to buy peace until you are more formidable. Civ V never forced me to do that. That's the beauty of SMAC. Factions are more proactive towards you. You really feel like it isn't just the AI on the other side. They have their own agenda and will pursue it with all means at their disposal.

Game has a very helpful tooltip tutorial on everything in the game. I do recommend reading the manual for more in depth understanding. You can also automate a lot of things if you find yourself overwhelmed, but where is the fun in that?

If you want to run the game in your native resolution, check out this thread: http://www.gog.com/forum/sid_meier_s_alpha_centauri_/how_to_run_alpha_centauri_on_an_1024x600_netbook

tbh this game kind of put me off within the first few moments of the tutorial. by the time i finished reading everything and got to play, i completely forgot what i read and didnt understand what to do.

i just gave up after that. civ 2 is the first civ game i started on and i found that fine to grasp and it was the first ever turn based strategy i played. before that i never played a game like this, so even a new concept like civ at the time was ok for me and i was only 11 years old.

now im 27... and after all these tutorials on this game im like... wtf do i do now then? i just don't get it.

The game isn't all that different from the rest of the Civilization series, though the first time I played it, I did find the graphics disorienting with the pink fungus everywhere. I guess you could watch a youtube video; admittedly the manual isn't as great as some of the other Civ manuals.
https://www.youtube.com/watch?v=9RhC0wlWsR0

I simply ignored what I didn't understand until I got the hang of it. You can get a Transcendence victory on the easier difficulties without knowing what you are doing and just building things. I don't recommend a beginner play against the aliens, but I recommend the original anyway.

The game difficulty does vary in the extreme depending on the random map

The game is pretty hard right from the start depending on how fungus is deployed in your immediate territory.... where you cannot go around fungus tiles, you can easily loose colony pods repeatedly setting you back massively, so you will definitely need save reload, at least at the beginning of the game.

Then the game will get quite easy once you expand a bit, at least until you meet your first (AI player) enemy at which point it will get quite interesting. I have not noticed any extraordinary capacity in Alien crossfire races but if your playing the original game and find the 'Believers' nearby on the same continent...... you have already lost the game, so unless your an expert player, your dead, may as well restart right there and then!

Any player can win the game, provided you block all the victory conditions except conquest. Because no matter how badly you play and how much you fall behind, the AI has a pretty low glass celing compared to other similar games, eventually you will catch up and overtake the AI ..... and on the subject of keeping up, one unit in particular new players should learn to use is the 'probe team'!

Alpha Centauri is quite similar to Civilization 2&3 concerning game mechanics. If you played one of these you should feel at home after a few minutes. It's more complex than both of them though so it'll take some time mastering the details. Biggest differences to Civ 4 are combat mechanics. Economy, city management, terraforming and so on are somewhat comparable.

Once you figured out how things work the game isn't that hard. The AI doesn't really get along well with the complexitiy of the game and can be outplayed easily even on higher difficulties.