Minecraft – How to apply a /gamerule before opening a world

As of the latest, latest snapshot (14w02b), this is most certainly possible. In fact, there's an easier way to do the whole thing now, which is awesome. With the /blockdata command added in the snapshot, you can modify and overwrite the contents of a tile entity (including a chest), and much, much more. The applications of /blockdata go beyond what I can fully comprehend at this point in time, but, for this specific case, it's not too hard.

Let's say for example your equipment chest is supposed to contain a notch apple, a gold sword, a bow, and a stack of arrows. The command for that would be /blockdata X Y Z {Items:[{id:322,Damage:1,Count:1,Slot:0},{id:283,Count:1,Slot:1},{id:261,Count:1,Slot:2},{id:262,Count:64,Slot:3}]}, replacing X Y and Z as appropriate. There's a lot of stuff going on in that command, but essentially, you are changing the data of the chest to contain the specified items. It's the same concept as using /setblock to spawn a new chest with these items, except instead of replacing the chest, you're overwriting its data.

In this more specific case, you want /blockdata 264 4 997 {Items:[{id:274,Count:1,Slot:0},{id:275,Count:1,Slot:1}]}.

And, of course, if you want an empty chest, all you need to do is use /blockdata X Y Z {Items:[]}

The problem was with the overworld portal.

After wasted a few hours more trying to rebuild the portal on the nether side, I decided to rebuild the portal in the overworld "few blocks away", didn't count how many because didn't expect it to work, but it did.

Then I placed the portal back to where it was and the problem came back as expected.

So I

• Step by step removed all adjacent blocks from the portal and tried entering after every removed type - didn't work
• Cleared more then just adjacent block - didn't work
• Rebuilt the portal one block upwards didn't work
• Rebuilt the portal one block inwards - had high hopes on this one because "few blocks away" worked - but didn't work
• Rebuilt 2 blocks inwards - worked, but - only once, after the next try I caught on fire. Thought it was because I activated on the left bottom step and entered from the right but after numerous attempts didn't manage to get it working again

Disappointed that 2-blocks didn't work, I built it on the other side of my little room 9 blocks away and it worked! Sorry I couldn't bother to try what was the minimum amount of blocks from 2-9, but I guess because the problem didn't appear on one certain block, the minimum amount wouldn't be accurate anyways.