I searched everywhere for a pre-patched version of Sonic Adventure for Dreamcast and found nothing. So, i decided to do it myself.
After digging through old tools, guides, and a lot of trial and error, I finally managed to build a patched version of Sonic Adventure for the Dreamcast using the DC image builder.

Game version: US 1.005 aka animated title screen version

Emulator required: Flycast

This patched version features:
• 60 FPS support
• Several bug fixes
• Draw distance fix (flycast only)
• Analog drift fix
• Skippable cutscenes and videos
• Widescreen 16:9
• Windy Valley Expanded