The Shrine

https://www.youtube.com/watch?v=DwYxZ_ky2fY

No Zero yet in the trailer though.

He's at the :32 second mark

I tried to play the first one, but I came away with the impression that this fan game is hard as shit and is only designed for Mega Man sweatlords and speedrunners.

I think most fangames assume you're some kind of cyborg enhanced human so didn't bother with the game but it at least looks like a well made game.

There's a footage of the fight against Zero in the first game but I mean he hasn't shown up as a playable or encounterable character yet.

Ah, there is a mod(Or maybe they added it as a feature alter) I think for the first one that lets you play as 8-bit Zero

Yeah I think it's an add-on. There's like a mode where you instantly die if anything hits you because we know only hardcore guys play these Mega Man fan games, though I think Zero normally doesn't take damage from anything unless he's attacking (he'd just block everything).