As you know there is a “Scene-Gizmo” at the right-upper corner in Editor.
Can I reuse that in game?
You cannot reuse any of the Editor windows in the game. The reason is simple: your game is shipped only with the stuff present in the unityengine.dll, and the editor stuff resides in the unityeditor.dll.
You’ll have to write the stuff you’re interested in from scratch, using the GUI or GUILayout methods from unityengine.dll (Editor windows also use these internally).