Those sound like cool projects! I hope future projects of yours make it to our archives

It's cool you can convert hex and decimal in your head. I struggle even with small numbers, so always think it's cool when people are good with that sort of thing. And pointers are important but tough to understand at first, so good job figuring that out! Keep it up!
One of my proudest programming achievements in the community would be
TokenIDE. I helped set the community standard of open source token files that can be user-edited to support custom libraries, and to this day the program is still used by people to make BASIC and Hybrid programs. It wears its age, and was clearly made when I was much more naive, but it's a cool project that effected change in the community for the better, imo, and laid the groundwork for the VERY cool ti toolkit tokens sheets, and paved the way for hybrid support as a first class citizen in IDEs.
Continuing in personal projects, I'm also quite proud of my
RimWorld mods, especially
Designator Shapes and
Expanded Context Menus. I did a lot of reverse engineering and learned a lot in the process of building these mods, and they are quite popular (Designator Shapes especially, with close to 300,000 current subscribers). Additionally, two of my mods ended up making their way into the base game in some shape or form. So it's cool that the game developer saw what I was doing and thought "yeah that should be in there" (and I know that's what happened vs. just a coincidence or already planned dev).
Additionally, I'm currently building a novel musical instrument. A chessboard drum machine. It's come a long way since this teaser video the composer put out:
https://www.youtube.com/watch?v=wNEp6VEgI0E. It's a pretty big undertaking with a lot of complexity and involves several integration points (COM, HTTP, MIDI). Here's a small demo of a more updated version doing weird stuff:
https://www.youtube.com/watch?v=4rkNsU5F5Tw. I really enjoy the intersection of engineering and art, and have a couple other
artistic endeavors that combine the fields.
For professional accomplishments, it's hard to choose. If you've ever used MyChart to look at xrays or access external data or launch an application, you've probably interacted with my code. Code I wrote helps drive the vast majority of integrations that Epic (the electronic medical record vendor, not the game company) has. Code I wrote helped optimize Pfizer's supply chain for vaccine development. I helped build the ACR's infectious disease imaging repository. This past year me and my team built two greenfield applications VERY quickly and the response has been fantastic.
Probably the single most formidable things I've written was a DICOM server that could handle the basic move and store commands as well as WADO image lookup from scratch in about a month, complete with a suite of tools for setup and configuration. It's hard to fully grasp the scope of that project without being in the medical imaging world, but it's massive.