Namco Museum Cheats for Nintendo DS
At the Arcade Menu go to Dig-Dug 2 then press L + Start to bring up the menu and go 'Hardcore options' in the Settings. Select 'New Version' and switch it to Old and when you go to the 'Arcade' menu you can will be able to select the old version of Dig-Dug 2.
This harder hidden version of 'Xevious' is unlocked by going to 'Xevious' and pressing 'Settings (2)' followed by 'Hardcore Options' and selecting 'Xevious'. Then choose 'Super Xevious' and 'Confirm' and when you now go to the Arcade and Score Attack menus you will be able to select 'Super Xevious'.
Go to pacman's hardcore settings and one of them will say stage 256. Turn it on and after you beat level 255 you will go to level 256 (kill screen)