Ariadne does have living as a slave but it can take a while to get to if I remember it right.
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is a promising(but not yet super far along) game where you live under an AI control and can get designated as a (unwilling) slave.
Degrees of Lewdity has various situations where you're basically a slave.
Many routes in
Knight & Princess are about getting enslaved and then trying to escape in some way.
Edit:If you don't mind the MC starting as a male
Queen of the Seas where you become a sexual relief slave on a pirate ship should be great.