Sega Dreamcast to this day is my favorite console ever. So many unique games.
I always felt the Dreamcast had to most 'Arcade' feeling with it's games.
You can almost just call the Dreamcast as 'Naomi Jr.'
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Piracy on Dreamcast was only possible because SEGA thought it was a good idea have a disc format called "MIL-CD" which is Dreamcast applications stored at the end of a Music CD. Those could have interactive menus/contents and videos playable with a Dreamcast. Because it's stored on the second session of the disc, the CD player (the main contents of MIL-CD discs are usually music) would never hit the Dreamcast data region.
http://blogs.yahoo.co.jp/rig_veda/49852246.html
This site has a picture with the eight legit MIL-CD titles made before the idea was canned and Dreamcast units had support to it removed.
Piracy was achieved by exploiting the MIL-CD boot mechanism to execute a loader which then would take control of the machine.
The games were protected against being loaded like this from scratch but obviously people had no trouble hacking them to bypass the protections. This was fatal for the system.