What error do you get exacty? Did you read the mini FAQ here:
http://gbatemp.net/t...ogamma-r9-beta/
And please use the lastet version of NeoGamma.
And something in general, the game should work in NeoGamma even if it's shrunken. Then you need to enable the 32K audio fix, which might be done automatically for Ikaruga. Also, if the problem was a shrunken .iso, NeoGamma should complain about this while loading, at least for this game as it uses .adp streams.
[...]As far as I can recall, ikaruga cannot be played as a backup.
[...]
My information is that it works, just without the background music.
[...]Also when intalling a cMIOS as XFlak told you, keep in mind that some retail games cannot be booted via the offical Wii channel. NEOGAMMA is needed.
For instance the zelda collector's edition is unable to load through official ways.
With my cMIOS i tried several games from the disc channel and they all worked. But i don't have Zelda Collector's Edition though. But that game is 1.an audio streaming game and 2nd a multi .dol game. And both things on their own worked if i remember correctly.
What you might be referring to are the cMIOS from WiiGator and Waninkoko with integrated loader. Those can't enable the audio streaming, so if you load a retail disc with those, you'll get an error as soon as the game tries to play an audio stream. My cMIOS does not have an integrated loader.