Unity Games EngineThis page is just getting started.
Unity has some online tutorials and kits to get you started at learn.unity.com Sign in to keep track of what you have watched.
Edit or change your skybox: Window>Rendering>Lighting Effects then edit or change the Skybox material
Triggering an animation with a keystroke
Some links to tutorials on collision and combat:
Brackeys’ introduction to Collision 05
Gameplay 06 and Score and UI 07
How to make a 3d fight game in Unity
BladeSmith BS combat system and BattleMancer BM weapon system
Creating 2D platformer – triggering sounds and other events