2d game with 3d models

Out of curiosity are a lot of 2d games put together with 3d models.
Looking at the animations on some characters they seem very fluid and detailed to be done as sprite animation .

If 3d models are used wouldn't this create a lot of wasted geometry that just isn't seen?

Just trying to clear in my mind what the norm is.

 

Its not the case everytime and no , not every game has 3-D objects until there is a specific requirement.
You can actually get the same feel as 3-D on 2-D except the parallax factor which you'll have to create by yourself for 2-D.

DOT-Art is one reference i can suggest.

 

There are a lot of reasons that a 2D game could be made using 3D models (sometimes called 2.5D), but it's far from the norm.

There are actually a lot of people now who feel alienated by sprite-based games, and often using 3D models can alleviate the strangeness perceived by these players. Besides that, you also have access to the possibility of realistic looking scenes and lighting and the flexibility of 3D animation.

To answer your question, wasted geometry isn't any more of a problem in 3D games with actors constrained in 2D space as it is in full 3D games. If any part of a model would always be drawn over, then that just makes that part unnecessary, so it can be omitted to save overhead.

As for animation, you can have sprites that are every bit as fluid as an animated 3D model, but it would probably take more work, and obviously they are limited to one perspective. If there are lots of animations for the character, 3D probably takes less time in the long run, but it really is more dependent on whether game mechanics necessitate 3D models and on what you want the feel of the project to be.

 

You're right about the wasted geometry. However if your objects are low poly and you design the levels well, it wont make a significant difference. I have seen people take side-perspective 3D animations, and render out 2D sprite frames from it. That way you get nice looking animation without wasting resources.

 

On modern mobile devices, Unity rendering is handled by the hardware across the board anyway, if I am not mistaken, so there's really no significant extra overhead just because something is "3D", as long as you are using standard shaders, or shaders specifically optimized for mobile. (As I Understand It)

 

I for one make 3D models in Blender, animate them then render them in 2D.