Besides the obvious spike in difficulty, is there any reason the leaderboard doesn't include an All 30 Challenges Category?

Side-note: I'm interested in running 1-15 soon! Would love to run it along with the rest of you folks playing this version.

Yes that's the reason some of those challenges are ridiculously hard.

Another reason is just the fact a run doesn't exist. It will be added as soon as someone shows interest and decides to do it. So far the only person to do a 1-30 run was BigBossMan on the N64 version. It is a difficult task so it scares everyone away lol.

Also nice to hear on your interst in running. We always welcome more runners of this game :D