The Steam Controller is designed to work with all the games on Steam: past, present, and future. Even the older titles in the catalog and the ones which were not built with controller support. (We’ve fooled those older games into thinking they’re being played with a keyboard and mouse, but we’ve designed a gamepad that’s nothing like either one of those devices.)
The Steam Controller was designed from the ground up to be hackable.
You can read more info on Steam's site
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