So if anyone is bored and would like to take on this project please by all means feel free. Sure there are things like MC Edit where I can copy parts of one broken world into another but the whole thing just clashes. Because if just one discontinues and someone else doesn't pick it up, my world could be trashed. There are a lot of mods I would like to try out which make new items, from new arrow types, to the aeroplane mod, to mining helmets, to pistons! However I will not, I doubt I will ever use these mods. It shouldn't be a major task for anyone knowledgeable in Java and the NBT format to at least make a utility to clean out non-standard IDs/entries.

Then once a mod had been updated the utility could reset the items/blocks to what they once were, thereby not erasing a persons hard work, while allowing a world to be playable regardless of mod dependencies.

Optionally the utility could make a note of the non-standard items/blocks and record their IDs and positions into a text file. It can either remove them entirely, or exchange them with something else, say a dirt block. The next simplest solution is to have a java based utility which will comb through a world and level.dat file and delete or change any unknown item/block IDs. The simplest solution is to wait for every mod to be updated but sometimes they aren't for a while or at all. When the client updates and doesn't have a new copy of the mod, the client doesn't know what to do with the new items and crashes. This is due to mods which add new items and blocks to the game, with new IDs. One of the main issues of using mods at the moment is making a world dependent on them, breaking said worlds when new updates come out. If a moderator would be so kind as to move it for us to the best location for this topic that would be great. I feel this thread should perhaps be under Mod requests or tools, not sure.

Save game cleaner mod