So my idea is to add an RPG-like skill tree to the game. Every time you complete a story from the beginning you gain a skill point for that character. Skill tree example:
Tier 1Hardiness (0/2)
Dick length (0/3)
Dick girth (0/3)
Tier 2Cum volume (0/3)
Cum force (0/3)
Tier 3 (Ultimate)Cum blast (0/1)
Big dick (0/1)
Hardiness: Increases the hardness of your erection (2 more verticle erection positions pressing P)
Dick length/girth: Small increases relative to default dick size of the character
Cum volume: Increases amount of cum player has available before needing to recharge
Cum force: Increases the force with which cum is ejected
Cum blast: For 30 sec player cums with insane amount of volume & force (activate, 2 min cooldown)
Big dick: For 60 sec player's dick is insanely large, like in the video on offbeatr (activate, 2 min cooldown)
If you combine non-linear story with this idea of "becoming more powerful" replay value would skyrocket.