Your video card is fine. I know you can run your game fine, but I'd have to say the minimum RAM would be 1 GB. In the making of this map, you have nooo idea how many graphics glitches I get when plopping hills/peaks and resources, some enough to block the whole screen. I used to get both MAF and memory crashes. Just now my progress was somewhat lost by a new error:
"Using the MemorySaver option in your configuration does not allow device loss. Exiting program."
I rarely have crashes right now, just a ton of graphical glitches which I can remove by saving, moving, varying on how bad it is. Worldbuilder IS harder to run than the normal game. There's also the game's size limit- the limit for my computer, or maybe for everyone, is 40000 tiles. If it's based on your computer's performance, the map won't load for you.
When I go in the map, look around, move my settler around, etc. the game runs fine. Same with turn times. But the true test will be having dozens of civs playing their role in history.
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The civs list (no leaders yet) and the resources list (no stats yet) can be viewed at the mod's new dedicated thread. Feel free to debate any inclusions/exclusions in the civs list. Since this map has more civs and resources to balance the longer map and playing speed, as well as other tweaks, I decided long ago to release the map only in conjunction with the mod. But it will be available early on in the mod's life.
http://forums.civfanatics.com/showthread.php?p=6473712#post6473712
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85% done elevations in Asia. Done everything in the middle east, central asia minus kazahkstan, and southern Asia (nothing of china).
I have 1 gig ram, a worse video card and a better processer, if not a recent one. On the plus side, you have a few months till the map is released with the first phase of my mod. A year and a half till the mod is fully ready.