ThornGhost got it.* (And I still had a ton of clues to give.)
- You strike out on your own.
- But you quickly gain companions (if you want any).
- You will need someone else eventually.
- Gotta
catch collect 'em all.
- Sexual dimorphism.
- Introduced some series staples.
- You might recognize some familiar faces.
- Most of them are not friendly.
- But one of them actually is (surprisingly).
- The Games Done Quick (GDQ) crowd would go nuts over this game.
- Royalty - can't live with them and can't cut their heads off.
- Oh, wait - that last part is not always true.
- Talk about a double-edged sword!
1. You start out as the young lone hero.
2. You can gather traveling companions in the same town that you start in. You technically don't have to take anyone with you (but it's a good idea to fill out your party).
3. Also, you will need a merchant eventually.
4 and 10 - you have to collect 6 magical macguffins which are ORBs.
5. The male and female versions of the classes can have quite different appearances (more so in artwork for the game than in actual in-game sprites).
6. It was the first DQ game with day and night cycles, class changing, Patty's Party Planning Place
etc.
7 and 8. Lots of staple enemies return in this game. (This could also apply to all of the palette swaps.)
9. I was thinking this applied to the Dragonlord but I can't remember if that's correct. (Sorry about that.)
11. You can't seem to go anywhere without running across a member of royalty who has an annoying fetch quest for you to complete.
12. You fight the multi-headed Orochi that was masquerading as the Queen of "Jipang"
13. The Double-edged sword is a cursed weapon in this game.
*I also would have accepted Dragon Warrior 3 as the answer.