Opus is the Western release of Takara's Plug & Play rhythm game Popira, released as part of Radica's Play TV / ConnecTV series. A few songs are shared between the two games.
Test Menu#
Booting the game while holding 1 + 4 + Start redirects the player to a test menu. This will not work properly on a soft reset, as the game will hang on the screen above. Furthermore, on MAME, the port IN1 must be set to Off on the DIP Switches menu.
At first, a checksum test is done with the game's internal, palette and sprite RAMs, with the latter seemingly failing on emulation.
Pressing any buttons while on this screen redirects the player to a color bar...
...and then to an input test menu. Holding a button for a small amount of time makes it be shaded cyan after releasing it. After all buttons are held, including the power button (which is configured to an unnamed DIP Switch above IN1 on mame), the background color changes to a dark green hue, upon which the game freezes after a few seconds.