Not a game, but a supporting peripheral.
CRT Monitor $15.00 at the local Veteran Thrift store.
Wife's CRT monitor died yesterday, so emergency swapped my LCD dual VGA input over. Luckily my old iMac has a built in smaller screen as backup. I never swapped before because of that two VGA input for my computer and Dreamcast.
Picked up a replacement, not a great monitor but not bad either, a 2005 model Compaq FS7600 17" monitor, actually 16" view area. No speakers, but iMac G3 has some nice Harman Kardon ones built in. Dreamcast will get its own dedicated amplified speakers. I have been wanting to play VGA Dreamcast House of the Dead with a light gun again. So finally now will get a mechanical VGA switch and spare VGA cable at Frys.
Unlike the LCD, CRT supports older OS9 640x480 256 color video modes.
Some LCDs won't support the lower res 640x480 of Dreamcast VGA.
Elusive CRTs are really getting hard to find, none sold new anymore.