Medal of Honor: Frontline

You'll unlock this on your second playthrough. If do this first, you'll unlock Full Frontal as well. You do NOT recover health between levels so if you are in the clear before the end of a level, search around or backtrack for health items. It is also possible to speedrun certain levels and totally ignore enemies, if you can memorize the entire level that is. On levels where you have the Gwebhr or Springfield rifles, they can be put to good use by sniping from afar. You can find my speedrun strategies HERE.

Also checkout Zolanton's MOH:Frontline Walkthrough on Hard

Bad Glitch: Again, I must stress that you MUST start a NEW GAME on your HARD playthrough or you won't unlock this trophy. To do that, select "Play" on Main Menu, and you'll see a small menu on the bottom right which has "New Game", "Save Game" and "Load Game". Highlight New Game and select it. Credits to Cheattaro.

Potentially Useful Glitch: If you actually reached the ending point of the level with zero health(like shot dead upon reaching there), the game then freezes as it doesn't know if it should load the next level or restart. You quit to XMB and reload your progress, and you actually start on the next level. In addition, you are INVISIBLE to enemies. You can shoot them from afar and they won't retaliate. They can still sense you when you are near and they can melee you and you die instantly. You also still die if hit by grenades and other explosions. Your health cannot be restored by walking over medical items, but only up to a certain period of time (or after a specific no. of deaths, both of which I'm uncertain what the exact numbers are) where this glitch will expire and everything then resumes as normal from thereon.

I have managed to pulled this off in these levels: Rough Landing, and On Track, but still I must say this is very tricky to pull off if you're actually targetting it. Still, I thought you should know this glitch exists as it might be useful.