Sonic Adventure is not broken. The physics and controls have aged pretty poorly because it was one of the first truely 3D games Sonic Team made. If you go back and compare it to the kind of stuff you could do in the 3D sections of NiGHTS and Burning Rangers, Sonic Adventure is just a few miles ahead. It is like how Metroid 1 has aged. That is not a bad game, but it seems like broken dookie compared to exploration based platformers now.
AS FOR ME?!?! I just put down Halo Reach because I noticed I was playing it for like seven hours straight and am considering doing it all day on Monday even. This was pretty much how I reacted that whole time:
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Also have been playing a bunch of demos on the Xbox Live Marketplace. Pretty much everything I played, even games I was certain I would enjoy, such as Comic Jumper or Sonic the Hedgehog 4 I did not really like at all, most of the demos of retail games I played I just did not even finish. It did not bug me though, stuff like Fist of the North Star was hilariously bad, so I still enjoyed my time.
I did however absolutely love Costume Quest. I need to pick that game up ASAP!