Quake mod concept: put the actual reasonable difficulty settings in a secret part of the hub, and make Nightmare mode the only easily accessible one. This way, the player feels rewarded for exploring.
Even better idea: the other hidden hub difficulties are also just Nightmare mode. The real alternate difficulties are hidden in a challenging, low gravity level ala Ziggurat Vertigo.
Everyone sharing that “87% of games are unavailable” study: this isn’t a time for doom about it. This is supporting information to broaden DMCA exemptions for US preservation institutions. Let’s use this to push for better regulations.