While it’s been possible for a while to get Sonic Adventure DX on Steam, it’s not necessarily the best versions of the game to get. To be more specific, it has problems like there being borders around the game and it having a low screen resolution. Which might have something to do with it being a port of the XBLA version, which was a port of the previous PC version, which was a port of the Gamecube version, which was a port of the Dreamcast version. So yeah, it could do with some improvements.
And it might finally get them, as SEGA announced today in a Steam forum post that they’re working on improving these Dreamcast Collection games over the next few months three years after they’ve been released. Among these improvements are added achievements, which can already be seen on the store pages of the games. Hopes up that this also means that they’ll finally add the Bad Religion back into Crazy Taxi.