The following options will make a huge difference: Any of the above could conceivably be crossdressers.

Any of them could have one or more transgender people or bifauxnen as potential love interests.

Just like in the Write a Magical Girlfriend Series entry, a male main character may be an Unlucky Everydude. Also, a main male character can sometimes be a Marty Stu who gets all the girls with no effort.

Therefore, you need to devise interesting ways for their feelings to develop. If your game will have one, then find a way to make it logical.

Note that harems do not necessarily exist in doujin visual novels.

Strive to add distinct elements to your game/story which will be obvious from the very first scene. It's possible to create a multi-path game with an Official Couple.

This might even make the other characters Pretty Freeloaders.

If you have decided to create an adult game, then you need to decide how sex will be incorporated into the story or the gameplay.

You can include hardcore scenes at important moments.

Or perhaps you want to mix some relationship elements into your mainstream video game. The first decision you make will unlock a major Event Flag for your story/game: If you're not creating a product with the intention of selling it, then know what you're getting into.

Do not talk about your awesome plans until your project is almost finished.

You could also make them bisexual if you want love interests of both genders, but don't put too many options or it can be overwhelming.