I started replaying Hadephobia recently and i found that map31 was supposed to have a ifferent track.
Here is what the wiki saids:

''Listed in credits.txt as "Royal Flush" by whitedamp, which is not played in-game and cannot be found inside the WAD. The TNT track is a placeholder track which was accidentally included because Chris Bourke (purist) had mixed it up with "Royal Flush" during compilation. The original music file can be downloaded separately from Xaser's site.''   Problem is that @Xaser's site is unreacheable right now.

So, anybody downloaded this song called ''Royal Flush''?
It would be awesome if somebody could stamp it here to archive it for posterity and for whoever wanted to manually edit their own Hadephobia megawad.

EDIT: Thanks to Xaser now this song isn't lost to time anymore ;)
Download from here or use the link Xaser provided

map31 - Royal Flush (v2) by Whitedamp.zip