This can be off-putting to some friends, so I usually warn them ahead -- you can always first check out the game’s demo to see if it’s right for you.
The Niflheim is probably one of the best free-to-play mobile otome game examples that I can give.
The game has a bold art style with intense flourishes, and while you play as a Shadow Every-Girl, all your your potential partners range from bratty kings to zombies to ghosts.
There's even a talking skeleton adorned with roses who will chat with you on occasion and give you romantic advice.
Compared to similar games on the app stores, this one has extremely good localization and copy-editing.
Generally you meet several characters, and will have to choose one to court.