Dungeons & Dark Souls
In the autumn of 2021, my household was collectively infatuated with the Dark Souls franchise. I was playing Dark Souls: Remastered for the first time, my roommates were replaying the series, and we would all take turns playing and spectating the others.
To celebrate Halloween, we decided to make it an evening of Dark Souls. We lit a bonfire, made Estus Soup, and I volunteered to be the Game Master of a Dark Souls-themed tabletop roleplaying game adventure. But I wasn't satisfied simply homebrewing adventure content for a game everyone was already familiar with, like Dungeons & Dragons. Instead, I modified D&D with new rules, classes, spells, and items to create a true Soulslike experience for the players.

The intent behind D&DS was to make a TTRPG system that honored the fantasy of Dark Souls without straying too far from the conventions of D&D that the players already knew. We only had one night to play, so there wouldn't be time for learning a whole new game.
When developing it, I considered adding new mechanics to be the most risky and cutting mechanics the least risky. For example, adding a new resource like stamina was highly complex and possibly not worth the cost. It was much more preferable to use existing mechanics to make new content that resembled Dark Souls. Then I could cut the original content it was made to replace to make it feel even more like Dark Souls.
To this end, I made the Undead Lineage, 6 classes, 3 spell lists, and 20 new weapons. I used the versions of these already in D&D as a baseline, then removed what didn't suit the Dark Souls fantasy.
Once the system was complete, I moved on writing the adventure. This was the easy part since I've been writing homebrew adventures since 2018.
I wove a classic tale with a forlorn maiden, a lovable npc ally, a tragic and terrifying boss, and a castle teeming with hollows and treasure. It was a memorable Halloween.
I usually write my adventure copies in a service called "The Homebrewery," but as this game was made to be as low tech as possible, I used pen and paper instead. On the right, you can view an example copy for a different Adventure I wrote in 2022 for D&D 5e.