Target Killing

Ye, this ^ ^ ^ . Your vague description could apply to every game from Space Invaders to Fortnite and probably thousands of other games I’ve never heard of

Obviously you have a game in mind. Go find tutorials for how to make that game in Unity. You would be absolutely AMAZED at how many people have already made massive detailed Youtube tutorials teaching you precisely to create (in Unity) clones of existing games that are actually even very new to the game market.

Work through two or three small game tutorials and you will soon know how to do this. Nobody here can press this into your brain. You have the do the work and learn the process. Learning is the modification of behavior as the result of experience.

When you have specific issues, come on back and ask specific questions.

How to report your problem productively in the Unity3D forums:

http://plbm.com/?p=220

How to understand errors in general:

If you post a code snippet, ALWAYS USE CODE TAGS:

How to use code tags: Using code tags properly