What the hell are the downvotes for? Seriously?
I didn't downvote you, but I wrote enough games to hope no young programmer takes your advice.
Games, as iteratively developed creative products, always interweave engine with content. Trying to write a generic engine in parallel to your game is a surefire way to never release a game.
Even if you set out in advance to write an engine, you should do like most market leading engines and develope a game first, then extract the engine out from it (Quake, Half Life, Unreal, Far Cry... the only counterexample I can think of is Unity, wait no wiki says "Over the Edge released its first game, GooBall, in 2005.[4] The game failed commercially, but the three founders saw value in the game development tools that they had created to simplify game development, and so they shifted the company's focus to create an engine for other developers.")
Sure, they are. In different files at a minimum, and likely within a separate directory tree in the overall project.
But not in a separate repository entirely!
Look at how the overall software industry is going towards monorepos. Not just (or even primarily) games, but software in general.
> Please don't comment about the voting on comments. It never does any good, and it makes boring reading.
Someone posted what they think is a reasonable answer to what I proposed and I didn't agree. I could expand on the discussion and haven't changed my mind. I thought we all came here to do that.
And you seem to be wrong about by comment about the guidelines. The other user was informed or reminded about the guidelines and we even had a nice little 'comment chat' about them.
Any kind of online forum inevitably requires participants to remind each other of the rules as it's the principal means of enforcing them.