PSO is no.3
IGNDC's daily Jap. top 10 has PSO listed as number 3 for December 22nd. At number 2 is another DC game called "Let's Make a J-Leage Soccer Club Expansion", which was also released on December 21st.

Sonic Adventure 2 Demo Available for download
From TSSZ:
That's right--AJ Freda has the guts to do it! You can grab it by heading to this link, but you're on your own as to how you get it from the PC to the Dreamcast.