when I was young, I was mostly messing around with tools to manipulate Doom and Quake data in QBasic.
also went about as far as trying to do Wolf3D style rendering in QBasic, but it was very laggy even drawing a single block.
by the time I migrated to C (by this point, in middle-school, ~16 years ago), I had migrated mostly to trying to write OS stuff.
however, the relative lack of coding skills (spent years essentially dealing largely with disk-driver, filesystem, and kernel-space memory-management issues) and the ultimate realization that I had little hope of competing with existing OS's eventually killed this.
I had briefly recently considered a partial revival of this project, in the form of an OS built around partial Win32 emulation with either native or emulated x86, but this didn't get particularly far. in this case, at best, it would have been a small hobby project anyways, more likely something unlikely to ever see much use out of (maybe) people running it in VMware or QEMU or similar.
after the collapse of the original OS project (~ 2003/2004), a lot of the code was re-purposed (initially with globs of code ripped off of Quake glued on) as an attempt at making 3D modeling and mapping tools (but they were never particularly good in a user-interface sense). and also my 3D modeling and mapping skills are terrible in-general it seems.
I didn't really start looking seriously into game-development into around 2010 or so, and then (for sake of being free of GPL), decided to drop all Quake related code and use my 3D tools code as the basis for a 3D engine, and then spent years mostly battling with performance issues (as basically, one may find that performance will often be eaten up by endless "little things", *).
*: something may seem pretty fast in-isolation, but may often be not-so-fast when workloads are scaled up a bit, and when competing for CPU cycles with lots of other "pretty fast" things (and profilers don't really answer questions like "what in particular is going on that is making my framerates not-particularly-smooth?...").
now, it is now, and this has been my life thus far...