Artifact importance...

That's pretty much what it is, a gamble.  It's all a matter of beginning/mid/late game and whether it's a rush map or not.  This question has been around since the beta, and it will never be answered.

I only explore when i have excess resources. Some artiftacts are really nice and worth a lot. But if you need every last penny to survive don't explore..

Howdidudothat said it best, its a gamble.

I wouldn't think of it as a complete waste of time since there is allways a chance o unearth the +damage% or plus armor% or + antimater% artifacts.

Another thing about exploring is that you may come across planet bonuses while looking for artifacts.

If you look at the SoaSE Wiki, someone has put forth an analysis on the value of artifacts and what they've found is that the Data Archive artifact is considered to be the most valuable artifact, since it reduces research costs by 25% and makes up the cost of searching for it the quickest. The Kinetic Intensifier is second, but fairly distant. As for the remainder, well, think of it this way: you got $1 as a consolation prize when you could have gotten $1 million.

If your advent, the research that makes it cheaper makes it far more worth your while. Add fully upgraded motherships colonization and you get free exploration.

Yep, with Advent it is economically worthwhile because of the reduced costs.  For everyone else, you have to luck out.

One of the best things you can get is not an artificact...it is a world with TWO trade bonuses!  If you do get a world with 2 trade bonuses, fill every slot you have on that world with tradeports, moving your other infrastructure elsewhere.   I remember this one funny game I had where I had about 10 worlds, but one of them had two awesome trade bonuses, so I loaded it up with 6 trade ports.  That world produced half of the credit income of my empire.

Generally, I find myself not looking for artifacts unless I am playing a very large map and am going through a period of consolidation.  I did once find the phase accelerator (+50% pahse jump speed in-system) as the vasari, which made travel through pase stabilizers (with 2 leveles of phase tunneling) go ridiculously quickly.  One tactical defense fleet could defend the entire empire.  In early game or on a small map, the credits and resources needed for exploration would be much better invested into infrastructure or ships.  Let the computer (or your opponents) do the digging and annex the planet they find artifacts on .

Are artifacts displayed in a hostile planet's data?

The timing is much research dependent as well - do you get bonuses cheaper from artifacts or research at a given point. Advent with its artifact bonuses, makes me think it's not that bad a faction, for large maps too...

As soon as someone finds an artifact, everyone gets a message saying "Another empire has discovered a powerful artifact at X." but will not say what artifact it is.

Searching for them is usually not worth it, but sometimes they can change the balance of the game if you've reached a stalemate with your opponents.

It is ok in SP. In MP they need to revisit the lottery.  In games where I know I can screw aroudn casue my opponents are terrible I may just do that with advent, get the reduce cost tech fast and use motehrship to research it for 20% of the price usually.

They are just there to add another level to the game. Not to say they arent useful, but in most MP games they arent worth the investment (personal opinion)

Against AI on al arge map, sometimes I indulge late game just out of curiosity.

manifest dominion can be nice too.  i was playing as advent against a hard tec ai who discovered this artifact, and its culture was kicking my butt until i went in and got the planet away from him

Only a few artifacts are actually usefull

I wouldn't waste my money unless I have loads of it. You should spend your res on ships and structures.

Perhaps there should be a small anti-culture bonus for the second stage, a sort of museum achievement?  Or the minor finds could be more common and/or more of them, as has been posted. 

Really, the only good reason to seriously hunt for artifacts is to go after the Archeologist achievement (find all 9 artifacts).

Admittedly, it was fun seeing a level 10 Kortul have a 200+ DPS from Pulse Beams alone with Power Surge (cooldown rate +75%), culture (+15% damage), research (+20% damage), and the Kinetic Intensifier artifact (+12% damage).

exploration gives you more than just artifacts, it shows you the planetary bonus.. and some of them are pure gold (like big trade bonus) or ponies.

The best artifacts imho are research (if you find it early.. good luck), culture and guns. All the others have thier use.. but not so much... but hey, its all free bonuses for all your empire! And its better in your hands than in the control of the ennemy!

And for advents, its so cheap to explore(with techs), you just gotta do it.

LOL...no, that is just the point.  It ISN'T FREE!  You pay to explore, which is why all the experienced players are calling it a crapshoot.  It is only free to Advent with research and a levelled up Progenitor, who we all say should do it.  Anyone else spending too much on exploration too early runs the risk of being killed by their neighbor who spends the money on military power.  Only in very long games with the AI can you afford this risk, because the AI is a lot easier to hold off than real people.

I meant that it affected your whole empire.. but yeah, it isnt free at all. Early on its not a great idea to do it.. 

I suspect that most of the people posting in these threads only play against AI and not online multiplayer, which is kinda sad.

I think it be nice if the game gave you hints as to what is where, even if you fail to find something maybe you should recieve a hit that tells you there is an artifact on a nearby asteroid or something.