I'd say each one is completely different, but if there's two genres that have required me to be fully aware no matter the difficulty, it would be RPGs and horror games.
Horror is self explanitory (everything is trying to kill you), but RPGs aren't thought of that much as being hard, despite the fact that this is the genre that made multiple saves necessary.
What's that? You didn't level out all your characters and decided to focus on one party? Sounds like it's time to split the party up. Oh... turns out that the skill set you selected sucks. Time to start over. Mmm, turns out that you can't go back to town and restock after that boss, as you've just been captured/the town is under attack. Pray or reload your save. Make absolutely certain you've got these spells, or the boss will destroy you.
I'm reminded of why strategy guides were necessary back in the day.
Runners up: Stealth, for obvious reasons again, and Platforming, a harsh, unforgiving genre.
Horror is self explanitory (everything is trying to kill you), but RPGs aren't thought of that much as being hard, despite the fact that this is the genre that made multiple saves necessary.
What's that? You didn't level out all your characters and decided to focus on one party? Sounds like it's time to split the party up. Oh... turns out that the skill set you selected sucks. Time to start over. Mmm, turns out that you can't go back to town and restock after that boss, as you've just been captured/the town is under attack. Pray or reload your save. Make absolutely certain you've got these spells, or the boss will destroy you.
I'm reminded of why strategy guides were necessary back in the day.
Runners up: Stealth, for obvious reasons again, and Platforming, a harsh, unforgiving genre.