Strange Planet by Nathan W. Pyle

I recently beat Halo Reach on Heroic without dying.

I recently played through Remnant 2 and noticed it had an achievement for beating just one boss (any boss) without taking damage. Given how much bullshit the bosses throw at you in the game, it doesn't surprise me it has the lowest achevial score in the game.

Also because I am still smouldering about it: The game's final boss makes Consort Radahn look like a bitch, when the second phase constantly blinds you and teleports you randomly between two different arenas and two variants of the thing you need to shoot.