When IC1 was initially updated to Minecraft beta 1.5_01, there were a few bugs that made that version a tab bit unstable. During that time, IC1 was hosted on the official Minecraft forums site. So, in the time between it being posted on the forums and the time that Alba took it down, some users were able to download this version to play with, despite the instability....
I never ran across the game-breaking bugs either, tbh. But I think those were mostly for the 'very primitive' SMP part of the mod...
