Having a challenging gameplay loop that is driven by player skill and knowledge of the game. In SKA you:
- Learn enemy tactics and how to counter them
- Decide how to spend your gold, balancing power gain with spending required to advance through the plot
- Decide how to efficiently use your materials to make your character stronger while making sure it's worth the expense
- Craft items you think you're going to use in future battles
- Either evade enemies, or decide which ones to remove from the map
- Decide when to use items that last for a day, to maximize your progress
- Manage Willpower and work around curses
- Make sure Corruption doesn't overflow, and ideally keep it low so it doesn't hurt your stats
- (Optionally) strategically use drugs, making sure it's worth the addiction and corruption cost
Almost none of this is stock RPGM combat, I'm sick of reading that. Not only is SKA one of the best options when it comes to gameplay in a H-game, it's a solid JRPG all on its own. But for someone not looking for non-H gameplay at all, obviously that aspect is going to get in the way of their enjoyment. I think just being in the H-RPG category sets up some player expectations that turn into frustration once they realize this really is a full-length JRPG that's in no hurry to get them off.
Admittedly, I think punishing the player by adding Corruption for H-scenes may have gone too far, and I think there is room for scenes where Aura does H without Corruption or monetary / stat gain.
Arguably the whole "Corruption is bad and needs to be spent" should have been automatic and not stat-driven, given that the Earth corruption is mostly linear anyway. Just let Alicia spend the points without danger of a Game Over or reduced stats.