A few years ago I wrote The Most Dangerous Writing App. It's been acquired since, but the open-source version still has a "hardcore mode" very similar to this,

A few years ago I wrote The Most Dangerous Writing App. It's been acquired since, but the open-source version still has a "hardcore mode" very similar to this, where you only see the last letter you typed: https://maebert.github.io/themostdangerouswritingapp/ https://maebert.github.io/themostdangerouswritingapp/