Edit: Welp, I'm an idiot. After posting, I stepped away and realised that the name of the config file had to be the answer.

The game is literally called colorcode. Found and installed it and lo and behold, the game's author is someone called Dirk Laebish, which explains the directory name.

Ah well. I'll leave this here for posterity

Looking through an old backup, I've found what appears to be the config file for some game or another at the path ~/.config/dirks/colorcode.conf, but searching the Internet (DDG and Google) turns up nothing for this, and searching apt, Synaptic (yes, I know they're basically the same thing) and even the online "wayback" part of Debian's package archive also gives no result.

The reason I think it's from a game is that the config file, despite its name, contains entries like GamesListMaxCnt and HighScoreHandling.

The only think I can think is that "dirks" is an acronym of some sort, which is why it's not showing up in past or present packages.

Based on the sort of games I usually try out and play, it's more likely to be a simple in-window puzzle or card game than a 3D game.

File dates seem to suggest 2021 as the last time I played / used it, whatever it was.

It would have been under some version of Linux Mint or LMDE, if the Debian commands didn't give that away.

Anyone have any idea what it might be?