From Bradyok Software:
XtremeWorlds (XW) is a powerful, free 2D MMORPG Engine/Maker. With XW you can make your own MMORPG with no coding in just minutes. If you find that the engine does not seem to have everything you need, you can code it in with our versatile scripting system. Unlike other free MMORPG creation systems, XW is updated regularly, so any bugs that are found are fixed immediately. XW has some great features, so please go check them out on the features page. XW is not an open source engine, but anything you feel that the engine is lacking can be suggested on the feature request section of the forums and will most likely be added.
What's new in this version:
Version 1.0.4 may include unspecified updates, enhancements, or bug fixes.
Very glitch-prone and accumulates millions of lines of errors in a single week.
The "creator" of this software is not an engineer; they hired other people to make it for them, then they tried modifying it themselves, only to intentionally create exploits and caused a multitude of glitches. Plus, they publicly announced they will not be working on it any further. This is an obsolete engine.
Again, I would like to emphasize that this software has exploits that the owner inserted into the program, intentionally. It will allow him to gain access to your entire server on which the server is hosted. This has been confirmed multiple times, and the "author" publicly admitted to it. In addition to being able to hijack your entire server, he can use your server to gain access to the host computers that are connected to the server through the client application.
TLDR; This obsolete software may seem nice for creating your own online games, however, it is full of bugs and contains an exploit.