Well, #22 and #21 weren't guessed yet, so new hints. And hint for new game #20.
#22: This game really only came to be because of a dare.
Hint 2: A dare because the lead producer actually wanted to just make an expansion or alteration of this game's predecessor, but that was something his director didn't want to do.
Hint 3: So the director used most assets from the previous game to craft something new and original, a side-story.
#21: One small village of indomitable ones still holds out against the invaders. And life is not easy for those who garrison the fortifies camps. So let's take back the country, province by province.
Hint 2:You do this by distributing the Magic Potion you get across your own provinces, and attack.
#20: Don't kill the scientists.
22. Majora's Mask?
21. Never played an Asterix game, but this has to be one of them.
My #23 is still unguessed:
#23: Pay a donkey carrots to get more corpses. A talking skull is your helper. Plant carrots, make wine, hammer nails, practice alchemy and create Zombies. The names for the DLC's for this indie game are puns on popular TV-shows like Breaking Bad, Stranger Things or Game of Thrones.
#22: Draw the map of the dungeon you find in a high school yourself. Guessed by The_Liquid_Laser.
#21: Silver haired maiden.
#20: Marry to get children you can send into fights to the permadeath.
#19 The second adventure of Ashley Mizuki Robbins.
21. Fire Emblem: Radiant Dawn?
20. Fire Emblem Awakening?