I only learned last month what dow2 gameplay looked like. It consists of Space Marines hiding behind trees until the ork waves stop. Advancing to the story check point, and hiding again. That's pretty ******* weak.
The 3D Sonic games, I feel, are better than their 2D counterparts. Sonic as a concept just works better in 3D, as middling as those games are.
Same genre. Just went from 2d to 3d in both of these cases
A change of genre is rare for a series of games. It's not often you see a puzzle game turn into an FPS, for example. Such drastic changes are reserved for spin-offs, not mainline titles. Fallout is a rare example, as is Resident Evil. In fact I would personally add RE to the list of franchises that improved, for a short while, after shifting gears. RE4 and RE5 were fantastic for their day.
Divinity did it twice first when it switched from Diablo to single-player action MMO and when it switched from action MMO to turn-based party-based co-op.