These are the Source files for IWBTG. They're horrible Multimedia Fusion files, which you will have to acquire to use these. Also be noted that several aspects of the game are broken in the current version of MMF2, such as vertical platforms. The upside is that traditional IWBTG crashes don't happen anymore. Due to the difficulty of doing anything in MMF2, these files are best used as reference.
This source code was used to create the impressive I Wanna be the Guy: Remastered, though it was mostly use for logic reference, as the whole game was ported to Game Maker.
IWBTG is under no particular license, and I grant you no particular rights. I do not even grant you the right to view these files. If you want to do anything with them, you gotta steal a little. If you're not willing to do that, then you really shouldn't be bothering with this to begin with. So don't @ me. I'm not gonna make it legal for you to replace everything with Tux.
My only request (and is only a request. I have no power over you) is that fan games, derived from this code or otherwise, not present themselves as sequels of "I Wanna be the Guy". Most fan games, due to my request, opt for the "I Wanna [Blank] the [Blank]" naming format. Many do not, and there have been several "IWBTG2"s.
Do as you will.
Due to Github filesize limits, the source is hosted off site on two different mirrors. This repository is only here as a point of reference.
https://kayin.moe/iwbtg/source/
https://drive.google.com/open?id=1u4XlbOaZtsE7WmnnlRemE5u1vAmfsvPt