I myself have tried to make a few games so I know a little bit about game development.
I'm going to summarize
First you need a engine ( whether it be custom or whatever)
You'll need tools like Maya ( I'm sure the big companies have something better but for us regular okes it should suffice)
You literally have to make all the objects using maya ( Characters, rocks buildings etc.) After making them you'll need to render them so you can texture them
After rendering them you'll need tools like photoshop to texture the objects and characters.
After texture work you need to rig it for animation and then animate it manually ( you don't have all the fancy motion sensing tech the big developers use to make those smooth animations)
Now that you've animated the characters you'll need to develop the levels themself and add the animated objects,rocks etc. to the enviroment using maya ( I don't think you have specific tools for the landscape)
Now you'll need to lay down the AI paths and actually do the coding bit of making a game.
This is also the part where you add the sound and various triggers ( Triggers being those scripted events you see in games like CoD)
After that render the level. Make the rest of the levels and render again until you have all your levels.
After this you'll need to make the menu's and code some more
I've probably left out a lot and I apologize its still pretty early and I'm no game dev
