I really like that tier idea! You're completely right in that there's always different crowds who want different things in DWRP, and honestly, that'd be useful even for the people who want the full-on dark fantasy. Maybe they've tortured their character for the last few months and now want to go easy on their character for a bit, so they can stay within the tier 1 and 2 choices. Maybe they like to mix it up and have some light and some dark prompts at the same time. Maybe they want to start off light, and slowly build up to the torture. That really caters nicely to everyone.

If you do wind up making this game, make sure you mention the tier idea in the ad plurk to hook people!