It doesn't seem like the parent wants to build an open source alternative. I remember reading about it over half a year ago (back then it was supposedly written in Go rather than C if I remember correctly) where there was also promise of open sourcing it.. His website also seems to indicate he now wants to go the route of SublimeText, so the open source promise should probably be interpreted as "I'll release the source code after I abandon the project, whether it takes one or ten years"..

FYI, I have nothing against closed source projects, but every discussion about eul.im seems to include the promise of open sourcing the project, which I'm sure is a great marketing ploy.