Action game:
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(the sequel is turn-based)
Non-action games:
School Conquest (not much actual combat iirc, but the enslavement and collection aspect is definitely there).
Harem Collector. More combat-heavy afaik, and has the collection aspect, but I'm not sure how many of the girls you actually fight directly to knock them out. Probably most/all you enslave them other ways.
Overwhored. Should fit the bill nicely. Fighting heroines, mindbreaking them and adding them to the harem.
Goblin Burrow &
I'll Borne: Haven't played them much, but thematically it seems to fit.
The Demon Lord's Treasure: As above.