We have to hand it to Atari for keeping it simple but functional early on. A lot of competing consoles around now tried to get crazy with controllers, adding things like number pads and spinning dials. This joystick and button is about as limited as you can get for a controller but is more than enough for the type of games that were coming out at the time. It served as a great starting point to build off of. Nintendo basically set the standard for all consoles going forward up until the 3D era...
