Archeaologist achievement

Is that the find all artifacts one?

Artifacts are random, by default there's a 15% chance that a planet will have one. The bigger the maps, the higher the chances of getting all of them

OK so for all maps the artifacts are random?  Does the percentage chance ever change?

It can be changed, there's a line in the map file that sets the percentage chance. But all stock game maps have it set at 15%.

It's random, but that 15% is one of the first things I change on my custom maps.  I usually set it up to 25%, which on a decent-sized map is enough to guarantee all artifacts by the late game.  (My most commonly-played map is a custom 69-planet 6-way FFA against Hard opponents.  I also modify the starting planet cluster and starting resources.)

Likewise, the default chance of a planet bonus is 40%, and I usually up that to 60%.  Planets are just more interesting when there's something unusual about them; I'm seriously tempted to set it to 100% so that EVERY planet has something to find.  In both of these cases I wish there was something in the Map Designer UI that let you adjust them, but it's easy enough to edit the text files by hand.

I have found that if you build a BIG map at least 7 to 9 stars and 300 to 800 planets you will find all the things to be found it just takes time

And how many weeks does it take to play a map of that size?  Seriously, I get exhausted on a 100-planet map, which is why my typical game is done on the 69-planet map I mentioned.  (I've reached the point where I almost never play any other maps in offline games.  Large enough to make rushing not viable, small enough to still be playable.)

Anyway, do the math.  12 artifacts, at 15% chance, would mean that you'd need 80 colonizable planets just to have an average of twelve artifacts across your empire, and you'd have quite a bit of duplication.  (That's assuming it's 15% per planet, not 15% per exploration, but the rarity I see in a typical game seems to bear that out.)  By the end of a game you'll control every planet, although home planets never have artifacts.  So, as long as you play on a map that has ~150 planets or more, you'll have all the artifacts you need.

Of course, if all you want is the achievement, there's nothing to stop you from making a custom map and setting the artifact density to 100%.  Even a fairly small (20-30 planet) map would probably have all twelve in that case.  I'm not sure what'd happen if you set it higher than 1.0; could you have multiple artifacts per planet?  (Probably not.)

Personally I used a galaxy forge modified map (ancient gifts). had it jacked up to 100% got multiplies of every artifact by the time I was done but I did it.

well I can proudly say that I reached the achievement today in the same 10-player game I also got the HAL I can do that achievement!  It was on the HUGE random stock map