http://steamcommunity.com/app/71250/discussions/0/34093781657096473/Hi all,
You may have noticed some new things crop up in our existing Dreamcast collection on Steam, such as achievements. Currently this content isnt accessible but its part of an initiative from SEGA over the next few months which is going to improve the player experience for these titles. We dont have an exact date for these improvements just yet but please bear with us, well keep you posted with more information just as soon as were able to.
Thanks for your patience.
SEGA
The Dreamcast Collection games being Sonic Adventure DX, Crazy Taxi, Space Channel 5 Part 2 and SEGA Bass Fishing. Sonic Adventure in particular has some pretty bad problems like borders around the game, no mod support and it being a port of the XBLA version, which was a port of an older PC version, which was a port of the Gamecube version, which was an improved port of the Dreamcast version. Also the Steam version of Crazy Taxi doesn't have Bad Religion.