I'm currently developing a forum ranking system for my forum (I won't list it here since doing so would be spamming) in which you slowly install more operating systems the more you post. You start of setting up the computer, going through a massive phase of DOS, then Windows then Mac Classic then Mac OSX and finally I'm gunna do some linux phases followed by less known operating systems.

For the 15 Linux phases I want to have 15 popular/well known Distros included. 5 will be in the easy/beginner phases, 5 in the Intermediate phases and 5 in the advanced phases. So I'm thinking:

Beginner:
- Ubuntu
- Linux Mint
- PinguyOS

Intermediate:
- Debian
- Fedora
- TinyCore Linux
- Arch Linux

Advanced:
- Gentoo
- Linux From Scratch

I'm still not sure what others to add and whether Debian and fedora should be in the intermediate phase... What do you think and remember that I'd like to also list them from easiest/beginner to hardest/advanced within their own categories too.

Thanks in advance for your help