If you've been playing PSO for some time, you may know that this page previously had a drop chart without any drop rates listed. This has to do with the way I originally developed the Enhancement Pack. If you would like a history lesson, feel free to keep reading. If you would like to see the original drop chart page from 2009, please click here.

I released the Enhancement Pack in 2009, and at the time, details for how to modify PSO were scarce, and tools for easily editing the game's files were even harder to come by. Most of the work I did to create the EP involved spreadsheets, a notepad, a calculator, and a hex editor.

The game's drop system involves two separate files: ItemPT controls the rates for common items, and ItemRT controls the rates for rare items. The final drop rate for a rare item is calculated using the monster's Drop Anything Ratio (DAR) multiplied by the drop rate of the rare item.

Unfortunately, the rare drop tables do not contain human-readable drop rates. Each monster's rare drop data contains the ID of the item to drop, plus the drop rate encoded as a value from 0 - 255. The game uses a secret formula to convert this number into a drop rate from 7/8 at best to 1/306,783,378 at worst. Without access to this special formula, it's impossible to know what the drop rates actually are.

I did not have access to this formula in 2009, so I had to edit the drop table by comparing my in-game knowledge of how rare certain items were against these "magic numbers" in the drop table to get a sense of how rare certain values would cause an item to be. I then selected new "magic numbers" for the drop table and did test runs while recording the rares that dropped in each run to get a sense of which items needed to be more or less rare. This approach naturally has limitations, since it's difficult to get a statistically reliable sample size without doing hundreds or even thousands of test runs, but there wasn't really any alternative without the ability to calculate the drop rates directly.

I attempted to incorporate the specialties of the various Section IDs into the chart, such as with Redria receiving a better drop rate of 1/98 for Standstill Shield compared with the 1/113 rate on the other IDs, due to Redria's increased ability to find frames and barriers. Unfortunately, without the ability to calculate the drop rates, some of these boosts have minimal effect, as with Pinkal receiving a 1/50 chance to get Madam's Umbrella, compared with the 1/55 chance on the other IDs. Some of these boosts even had no effect at all, as with Luminous Field: it turns out that certain "magic numbers" in the ItemRT file produce identical drop rates, so even though I gave Redria a higher "magic number" than the other IDs, the final drop rate for Redria is sadly unchanged in this particular case, and every ID received the same 1/585 drop rate.

For people who are familiar with how the drop files work, it may appear strange to have TP Material as a rare drop. The ItemPT file contains space to define a rate for TP Material, which is how it is able to drop in Challenge mode. Since I didn't have access to an ItemPT editor in 2009 to examine and edit the tool drop table, I instead added TP Material as a rare drop for boxes, since the ItemRT file is much easier to understand and modify with a hex editor.

PSO development has come a long way since I released the EP in 2009, and much of this information is public knowledge now, and the game's files are much easier to edit, too. You can even find Sega's magic formula for generating ItemRT drop rates in the Sylverant source code. I decided that in the interest of preservation, it was time for me to calculate the drop rates and create my own proper EP drop chart, so that players in the future would have a better idea of how the EP came to be and why it is the way it is.

If I had access to the tools of 2025 back in 2009, I could have done a lot of things differently, but of course progress only moves in one direction. The EP drop rates are easier than I would have made them if I had known how to calculate the rates, but since rares don't drop in quests by default, I still think high drop rates are better than low ones, due to the limited spawns available in the freeplay maps.

The Enhancement Pack is a product of its time, and while it has plenty of problems and limitations, overall I think it turned out quite well considering the limited tools and information I had to work with at the time, and I thank everybody who has enjoyed using it over the last 16 years. Here's hoping it continues to help people enjoy PSO Ver.2 in the future.

— Aleron Ives
July 2025