Why Prototype without Assets?
Making the Prototype with “programmer art” allows the programmers to focus on the game’s core functionality and get the vertical slice or proof of concept proven and working before any time or money gets spent on high-quality assets.
The only problem is that prototyping without the final or close to the final assets can cause problems depending on the type of game and how dependent the mechanics are on the final assets. That can cause a lot of time wasted changing the mechanics or the assets to make them work as intended.
An example would be a 3D 3rd Person game where the character and its animations are the game’s primary focus. You would be able to get some things done with programmer art, but there is a cut-off when you need a character model.
Is it a good idea to prototype without assets?
Yes, it is. The only thing you have to keep in mind is where the cut-off point is that you need to bring in the assets to continue building the mechanics to prevent too much time spent changing the mechanics to fit the assets or assets to fit the mechanics. This point is different for every game.
