Guitar Hero & Rock Band are pretty popular games, not your typical shoot-em up entertainment.
The controllers are pretty simple, a few fret buttons and a strum button. With a PS->Atari adapter, you could use existing guitars rather than make new ones. The whammy bar is nice but isn't really necessary. You could scale back on the fret buttons too to simplify it.
The note dropping is pretty basic as seems within the realm of the Atari's capability, but I'm not a coder. I used to play a lot of Kaboom. That seems similar enough, or something like River Raid. You don't need all the fancy 3D background graphics for the basic game. Just two vertical fret bar columns. A star power effect could be one of those psychedelic border patterns, not sure of the official term.
The current band games focus on Rock music. They neglect other types. As for a homebrew, music licensing would probably be prohibitive. An atari version could tap other styles of music within the public domain. There are a few christmas games in the atari-age store. A jingle-bell edition with holiday music might be nice. Or one with available atari game themes.
Can the 2600 handle music for more than one player? Maybe a game like this would be more suitable for the 7800. How many songs could be stored?
Difficulty could be easy or hard with the difference being the speed of the notes dropping, and/or the use of 3 vs 4 fret buttons. Maybe a loop length for the songs could be an option. Play songs through more times for high difficulty.
Miss too many notes & song fails. Score points on number of notes hits. Atari Power for extra points.
I think it's amazing that folks still code for these classic systems. Hats off to every one. I still have a 2600, 5200, 7800 and Jaguar and have bought a number of games through atari-age for these system. Keep up the great work. Thanks.
Jaeson K.