Barbearian

And even though it's basically the same thing over and over again, there's enough progression and variation that it rarely seems boring.

The 12-second powerups are color coded: Blue-indestructibility; Pink-an auto-melee attack 'ball' spins around you annihilating everything immediately around you as you move; and Green-much faster movement and melee attacking.

You can thoroughly customise the difficulty with several sliders in Options, where you can also find some helpful accessibility choices.

It's well produced, though potentially a little loud compared to the sound effects with the default volume settings (easily adjusted), and though it's not hack-and-slash like in the least, it does somehow fit the game well.

There are all the usual options -- including full controller support and remappable controls for keyboard as well -- but of note is the Accessibility menu.