> MAME has an incorrect 256x224 resolution for this game instead of the correct
The reported resolution at startup is not necessarily the final resolution; Megadrive hardware games (including this one) can and do switch modes during runtime.
If you believe that is not happening, then we cannot psychically debug your configuration; you'll need to list the MAME version, operating system version, and the relevant bits of your .ini file (especially your -video and -(no)window and -resolution settings). Plus a more concrete description of what is or isn't happening that you believe to be wrong.
-R. "Good Cop" B.