In the 5e game I'm playing in, there are three Dwarves, two half-elves, and a Goliath. The Goliath is definitely the outsider character.I think an outsider race (lizardfolk is a really good candidate IMO) would ad some variety... aaaaand you know some players really like to play the outsider, it gives them an outlet to do that.
I think that's it right there.An alternate alignment system isn't such a terrible idea in this regard.
In fact, something like this certainly gets more at the heart of "who are you and what drives you?" than the classic alignment system does. "good" and "evil" are so hopelessly nebulous and "law" and "chaos" can be entirely unhelpful too as it often depends very much on where the rules on coming from in regards to a character's likelihood to obey them. And someone saying that they follow their own internal code is well... totally not helpful, everyone follows their own internal code.
If it is a Goblinoid Empire, this shouldn't be too hard. Empire implies rule over people other than your own (as opposed to kingdom, which typically meant a more homogeneous population). The Bourbon Kingdom of France vs the Hapsburg Empire. So it isn't inconceivable that your Goblinoid Empire has an elite Elven archery unit drawn from conquered elven lands. Something like the Jannisaries. Or maybe a dwarven mountain unit, or a halfling spec ops team.I've been going back and forth on that. It might be fun to have one "outsider" race, like orc or lizardfolk. But if I want this imaginary campaign to be focused on the story of the Goblinoid Empire, then it would be interesting to limit it to goblin races.
To add some variety to the three goblin races, I could borrow subraces from other D&D races... Maybe some Gnome and Halfling subraces for the goblins, and so on.
Love these ideas!If it is a Goblinoid Empire, this shouldn't be too hard. Empire implies rule over people other than your own (as opposed to kingdom, which typically meant a more homogeneous population). The Bourbon Kingdom of France vs the Hapsburg Empire. So it isn't inconceivable that your Goblinoid Empire has an elite Elven archery unit drawn from conquered elven lands. Something like the Jannisaries. Or maybe a dwarven mountain unit, or a halfling spec ops team.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.