Special items included: Unreleased titles, prototypes, NTSC conversions of PAL games, and bug fixes.

Items removed: Non-working dumps, duplicates, prototypes or demos of games that eventually saw a full release, European versions of titles when a North American version was available, and homebrew games.
Additional information:

Release notes: It was a common practice for companies to "clone" games during this period, changing only a few graphics or colors and then releasing their own version. However, depending on what region or market you lived in, you may remember one game but have never heard of its clone(s). Cloned games that have significant graphics or gameplay changes are included because of this, as are the "gender swapped" versions of some titles. Extremely similar bits of data between clones and their originals may trick your emulator into thinking you have multiple copies of the same game. However, I have replaced as many titles as possible that conflicted with each other, regardless of their names, and only one title will match one given game. If you find duplicates in the names or artwork when loading your game list, right click on them to find out what name / game ID each one actually reflects.