[lmz]

While "solved" is a bit optimistic, it is also true that e.g. sports games get sales every year with mainly updates to the player roster.

[Ekaros]

Or many locked in formulas. Think CoD, BF somewhat, Assassin's Creed. Whatever Ubisoft does.

[KptMarchewa]

Decent amount of BF games flopped. Assassin's Creed had three "reboots" of the formula. Ubisoft recently realized they have to shake things up, since flops are more and more common.