If you have completed this game and are seeking greater challenges, look no further! This program allows you to design your own challenges without the hassle of modifying xml files. Challenges are fully customizable; you can choose from all of the options that the game has to offer, with some limitations (listed below).
For easy sharing, challenges are individually stored in "challenge codes". These codes are designed so that it is easy to identify its name and author at a glance. That being said, DO NOT directly modify challenge codes, as a small error could make the code unreadable by the program. Instead, use the "Edit Challenge" option in the program. The program also has the ability to save and load challenge codes to .txt save files for easy organization.
These challenge codes can then be read by the program and compacted into one xml mod file. Every generated xml file works just like any other mod; simply drop it in the resources folder in your Binding of Isaac game file.
Lastly, the program has the ability to modify save files, allowing codes to be added and removed without any potential corruption.

The various features and settings configurable in the challenge creator are as follows:
+The character (includes characters like Eden and The Lost, and even "hidden" characters Black Judas and Bloody Lazarus)
+The card, pill, and/or trinket(s) the player has
+The items the player starts with (this comes with a filter system and a search bar so you don't have to sift through 300+ items)
+The challenge goal (this includes ???, The Lamb, and Mega Satan)
+The curses afflicted on the player every floor
+The rooms not generated in the challenge (for example, most challenges remove treasure rooms)
+Whether or not the player can shoot tears
+The difficulty of the challenge: normal or hard
+Greed mode challenges
+Some other minor features, such as maximizing damage, blacklisting curses, adding coins, etc.

However, there are a few limitations that should be noted:
-Only one (specific) pill and one (specific) card/rune can be added per challenge.
-There is a limit of 2 trinkets (you can never have more than that in the main game, anyways) and a limit of one active item.
-There is no way to create custom characters or remove default passive items.
-There is a limit of 20 loadable challenges per xml file.
-There are a lot of things that simply can't be added because the default challenges don't use them.

A few extra notes (this is basically the FAQ--this list will expand as questions arise):
)The name, author, and description that you specify within the program are never displayed within the game itself. Instead, a list of the default challenge names corresponding to each challenge loaded will be presented whenever you generate an xml file.

That about covers it for this program. Please report any bugs that you find and provide feedback in the comments below. I'd prefer that you don't share your challenge codes here; instead, share them on this mod's /r/themoddingofisaac topic:
https://www.reddit.com/r/themoddingofisaac/comments/41fwrv/the_binding_of_isaac_challenge_creator_v20/

I hope you enjoy the mod!