The original Steam Controller underwent many changes. The final 2015 version differs significantly from the first prototypes of the Valve device.
Recently, a user under the nickname Waste-Set5032 shared an unexpected find with the community. He said that his father discovered a Steam Controller prototype in a Goodwill thrift store:
This is really cool for me. As a teenager, I didn't experience Valve's heyday, so these things are genuinely interesting to me.
This version of the Valve gamepad is known by the codename "Chell" — after the main character of the Portal franchise games. The prototype dates back to 2013-2014.
For comparison, this is what the 2015 Steam Controller looks like:
A few months ago, Valve started selling a new version of the Steam Controller. This version is more reminiscent of classic gamepads: it now has two sticks with trackpads underneath, a D-pad on the left, and four X, A, B, Y buttons on the right.
Also this year, Valve launched another device — the Steam Machine. Players are lining up to buy the new product.