Do I need to compile the engine source to create a game in C++?

So far I only downloaded the editor directly from Epic, but didn’t download and compile from the source myself. When I launch the editor it gives me the option to create C++ projects. If I choose one of them, I get a VS project that I can build to start and use the editor. However I never actually built the editor itself (the VS project compiled in about a minute or so).

So is the Editor somehow able to “inject” the game code and run it just like that? Is this a valid programming setup, if I don’t plan to modify the engine code itself? Or am I doing this wrong? In all the C++ tutorials I found, people start by compiling the engine. But I don’t actually want to modify the engine, just write a game on top of it.

Nope. You can create a C++ only project when you launch the editor the first time. This does not require the full source code.