Back in 2012, I bought Bastion which had just been ported to Linux with the help of Humble Bundle. I'm not a huge gamer and I'd much rather play with my PS3 controller than on my laptop's keyboard. So I wrote some code that would emulate a keyboard on Linux with UInput. All I needed to do was read joystick events and translate them into keypresses that Bastion would understand. :-D
It was kind of playable for a while except with firearms that it was hard to actually - you know - point at enemies... Plus Bastion added support for the Xbox 360 controller about a week later so it was easier to just go out and buy one!