Disagree. Gaming is so diverse there is no rule of thumb. A game like The Secret of Monkey Island is fun and follows a different formula altogether from Dark Souls, which is also fun.
The only thing every game needs is passionate artistic direction as opposed to modern monetization. Halo 1-Reach was made by a bunch of dudes that loved games and who wanted to make fun games. That was it. No rules, no MBA theories, no diversity consultants, just passionate creativity. Look up on YouTube Martin O'Donnell's explanation for how they came up with the "I Would Have Been Your Daddy" skull. It's passionate details like that that made the whole game great.
Halo 4 and onwards were made by the exact opposite mindset and it killed one of the greatest franchises in gaming.