I finished the Lost Relic on easy mode as have Wolfercooker. Wolfercooker, because he's best bros with the authors of the game, and me, because I like a good challenge.
For The Lost Relic, it's about yes, saving and loading often, knowing when to use what weapon in what way, and recognizing the boss AI weaknesses. (In the last level, knowing how to dodge projectiles and sprinting instead of normal running is important). I've yet to finish the game on hardest. (My save file died halfway and I never replayed on hardest after that.)
My guess here is that only Wolfercooker and I actually finished the game because the rest of the people either can't play the game because it glitches out, or ragequitted.
HELL, you know what? If you want a real challenge, (although not as hard as The Lost Relic), try SHS which I made a few years back:http://www.wolfenstein3d.co.uk/adds_STU2.htm
And of course, try the hardcore version on hardest difficulty. Unlike The Lost Relic, I've actually beat each level starting with 8 rounds and a pistol, so I KNOW it's actually humanly possible to beat. The Lost Relic on the other hand, is still a question mark. (Maybe if I knife some bosses, but that's seriously hardcore right there!)
I can't play this, it's not in SDL though.