I have used 3D models in the very start of a game project. This is not necessary. I recommend the exact opposite: Don’t hire a 3D/pixel/gui/other artist to do graphics in the beginning of your game project.
– The graphics will most likely change anyway – that means the artist needs to re-do his work
– You don’t need final graphics to test your gameplay: you can use placeholders to test your game.
Instead of a human model have a 2 unit tall blue box moving in the screen. Instead of having an elven warrior fighting, have a 3 unit tall brown sphere moving on the screen. You need trees? Use green cones to represent them. Same goes with the graphical user interface: you don’t need animated button to “Start a New Game” – you can have a white box with a black borders and times new roman text: “START NEW GAME” in it.
Use of placeholders will benefit in the following ways:
– It enables you to test your gameplay faster (as you need to tweak the graphics later when the core game is done)
– It saves time, nerves, money or all of them as your artist doesn’t have to re-do his job over and over