I've worked for a major game publisher and the numbers showed that only 10% of the users actually played the single player campaign . This was 3 years ago. I'm not surprised that publishers have been trying to get away from it for some time.
Edit: I should specify that this is for first person shooters.
You could probably play the beat game with a dance pad. Sony had a requirement that games be compatible with all peripherals. I'm sure there were a few exceptions though.
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