Thanks so much for this...just what I've been looking for to continue messing with my very old world. Like the best things in life this was simple and easy to use and I am very grateful that you shared your work. :smile.gif:
So, today my little brother decided to make a puzzle map using the new Creative mode. However, after he made his, he released that he couldn't play it in Survival mode. This upset him greatly, so I decided to make a solution and create a program that switches your world's game mode. The program has a nice, simple interface, and it's easy to use. I realise that there probably are in-game mods that do this, however some people don't know how to install mods or they don't feel comfortable using them.
The Clear Inventory option lets you pick whether or not you want to clear your inventory after you switch game modes. Useful if you don't want the infinite items from Creative in your Survival map.
Note: You must have Java installed in order to run this program.
Download the program from the link below.
Save your world and close Minecraft
Run the program and click the "Browse" button
Pick the world your want to change and select it's "level.dat" file