I believe there's 3 control pads that made a change in the videogame history, the nintendo control pad,the super famicom (super nes) and the playstation dual shock. (edited after a chat with leoman)
Famicom Control Pad
The first and probably one of the first that changed the way we played videogames, the nintendo (8 bit) control pad, before people played with a joystick (atari, coleco, etc) this was one of the first controls that changed the way we played video games including A, B, Start and Select
(thanks to leoman for the very acertive reminder)
Super Famicom Control Pad
Why do i affirm this? is simple, before nintendo released a revolutionary pad with 4 buttons and two buttons in the top (for the pointer fingers) everyone was used to play with just A,B, start and select.
Truth, Sega Mega Drive had a 3 button control pad, but many developers never used the third button, later as the super famicom was such a hit and a great innovation sega released a 6 button control pad... again, without any success (beign a sega fan, i have to admit, it was a failure)
Sony Playstation Dual Shock
Now the dual shock, i know many systems released different and sometimes odd control pads but is a fact the dual shock from sony was the reason for the innovative control pads for nintendo 64 and the sega dreamcast, but proof of the dual shock success is how is still used in the playstation 1 2 and 3, a control pad that made a revolution and has survived varios game system generations.
some of the features as the 4 buttons for the pointer fingers (based in the super famicon control pad) the neat and smooth analog control, vibration pack without the need of of a vibration pack (see nintendo 64) all this and more made this control pad a winner!
Hace 14 horas