My friend sent me a zip of a world he created, claiming its 100% survival, but I'm suspicious. Is there any way of figuring out if he used creative at any point (there don't seem to be any creative only blocks in the world).
I know on Xbox you can't get achievements if you ever used creative, is there a method like this for PC.
You could look at the statistics, which are stored with a world, in the stats subfolder, and check to see if the numbers for things like blocks mined/crafted/placed and tool usage are consistent (for example, the stone needed to make the stone-based blocks they placed should use no more stone than was mined/picked up, same for wood, and you should see that they crafted them and the usage of tools should reflect the amount mined); an unusually high "distance flown" stat may also be suspicious (note that this does not just count Creative flying so a nonzero value is normal; for example, here is a screenshot of my stats (from before I modded the game to only count Creative flight due to somebody claiming that I used Creative because of this stat. Of course, mods can also be used to cheat without making it as apparent, but I'd still expect the stats to show anomalies).