Mail Mole
Thymesia
Mortal Shell
Perish
The lost hero of nostalgaia

I completed all of them except perish on temporary free trials & they are all really good

None of them required in game purchases although I did not complete perish to know if they sneak in game purchases in

All except mail mole allowed you to "grind" or upgrade the character through repeated actions to make the game easier but if you are skilled enough I believe it might be possible to complete all of them without "grinding"