THE HOUSE OF THE DEAD: Remake

This would easily be the hardest achievement in the game if not for the cheat codes. Use the God Mode cheat (as well as Infinite Ammo and One Shot Kill) to make this achievement trivial. I should note though that God Mode seems to be a little finicky. I have had instances where I still took damage from an enemy despite the cheat being activate (and working against other enemies). I suspect this has to do with killing scientists, which causes you to lose health. I'm not entirely sure if killing a scientist voids this achievement, but I would recommend saving them (or just letting them die) rather than killing them with, say, the grenade launcher. It's therefore pretty simple to pair this achievement with the same run of the game where you save all scientists. That's also the shortest path possible, since saving scientists typically leads to a shorter run through the game.

If you decide not to use cheats for whatever reason, this will be decently challenging, especially against the final boss. The good thing is that you can break this up by chapter, similar to other full-game achievements like saving all scientists. By that I mean if you do take damage, quit out to the main menu and then choose to Continue. You'll have to start the chapter over, but it's better than starting the whole game over, and it lets you take it one chapter at a time instead of having to do the whole game start to finish without getting hit. What's also nice is that there is nothing randomized about this game whatsoever, so retries in this manner mean you can eventually lean where all enemies are and who to shoot first to ensure you don't get hit. Without cheats, it's really just a matter of practice makes perfect.