My personal favorite activity in Hyper Light Drifter was the ||secret arena||. It would be cool if there were secret\non-secret arenas. They could perhaps drop holobytes related to the environment\enemies it's in as a reward, or maybe a mid-run shop/upgrade or even a special other event.
#Arena Battles
mortal sky
primal helm
That's how I knew it would work as a rogue! I spent my last 10-20 hours on HLD just doing the 100 foes challenge