There are two difficulties in this game. Normal and Survivor. Survivor basically gives you less resources and you will be restarting from a "save point" rather than a "checkpoint" way more often. Normal has a safety net where you can retry the same spot 3 times if you don't have a retry item (they look like video recorders). So yes, the game may be a little more difficult but nothing you can't handle. I'd just suggest throwing it on this difficulty and figuring it out as you go along. The game is still going to give you a tutorial and whatnot. Plus you can still find the retry video recorders in the game.
Glitchy: There are several incidents where people have completed the game on this difficulty and it did not unlock, while others unlock it fine. So far the only fix has been to complete it a 2nd time. The only other idea I have at this moment is to copy your save over to cloud or USB and try to beat it a second time at a save point that is at the final moments of the game.