Personally I found the mechanics from some other games (like Magical Girl Celesphonia, and other games from No Future) that are nicely done for RPGM battle-sex
1. Percentage-based pleasure meter, with the CG of character getting more heated-up as she goes near orgasm
2. Don't do defeat-upon orgasm. Give "dazed" debuff that last a few turns and maybe "wet/stained clothes" debuff
3. Clothes durability meter & "embarassed" debuff
4. Enemies have to use 1 turn to prepare/approach before restraining. When restrained, MC needs to use a few strength-based strikes to corrode the restrained (a lot of games use chance-based, which is annoying)
5. Enemies may cop a feel without restraining the MC. But they can only fuck when MC is restrained
6. Have multiple protagonists in a party instead of a single main character. The party have more than 1 female characters that can be sexually attacked. Can also have male protagonist characters that sexually harass the female character for buffs, or to distract the enemy to get crit-chance
7. Kidnapped protagonist system where died protagonist can be saved. They are tortured and can be seen progressively the longer it takes to save them