If one wants to have a glimpse how much "fun" it was,

"PC Intern: System Programming : The Encyclopedia of DOS Programming Know How"

https://www.amazon.com/PC-Intern-Programming-Encyclopedia-De...

With examples in Assembly (MASM and TASM), QuickBasic, Turbo and Quick C, Turbo and Quick Pascal.

They aren't sidestepping the garbage collector nor the C# safety checks for the whole engine, because HPC# is only used in a very focused area, everything else is plain old C# as always.

I can also state that in the old days C wasn't worthwhile to be useful as a programming language to write game engines, because proper game engines were written mostly in Assembly with C, Pascal or Basic as their scripting layer if at all.

For example,

https://www.atariarchives.org/

https://www.amazon.com/PC-Intern-Programming-Encyclopedia-De...

Still have my copy of PC Intern[0] from which I was able to learn how to do the same.

[0]http://www.amazon.com/PC-Intern-Programming-Encyclopedia-Dev...