Take a look at the Azeron Cyro. It combines a high quality mouse, a ton of programmable buttons and a thumbstick, so it has everything you need for one-handed gaming in the vast majority of games. Might not be what you’re looking for, but it’s good to know that there are possibilities that you probably haven’t considered yet. It even comes in a left-handed version.

Which problems? As far as I can tell this solves zero problems for users of websites. Wanting to replace captchas with this is just another arms race that normal users will suffer from.

Hyper Light Drifter really deserves a mention too!