Speaking of Unity packages, here’s one I add to every new project: Unity Extensions. Whenever I find myself wishing an API existed for a UnityEngine type, I add it to this package as an extension method. The result is a small collection of utilities that make working with Transform, Vector3, and so forth more pleasant.

Say you want to set the Y position of your player to zero. You might write this:

transform.position = new Vector3(transform.position.x, 0, transform.position.z);

// Or:
var position = transform.position;
position.y = 0;
transform.position = position

With the Transform.SetY extension method, you can write this instead:

transform.SetY(0);

Another example. Given a list of enemy positions, you want to find the one closest to your player. Not difficult, but you may appreciate this short version:

var closestEnemyPosition = transform.position.GetClosest(enemyPositions);

Take a gander at the README for a full list of extension methods.

Exciting? No. Useful? You bet.