I haven't logged into Steam for several days now. All my gaming recently has been rRootage, which I recently rediscovered after looking around on Flathub for unrelated software.
This is an old favourite of mine. Years ago in high school, I snuck it onto some computers and later saw it on others, so people were definitely copying it around.
rRootage is a bullet hell with all the extra stuff ripped out. Yeah, that's just about all there is to say about it. There are no minor enemies. Each level is a rush of five bosses. Each difficulty, from 1 to 9 then 0, has three hand-crafted levels, plus a fourth where the bullet barrages are created randomly using a genetic algorithm! All my footage here is captured from my attempts on difficulty 8. It features four game modes. There's a "normal" mode plus three modes with mechanics inspired by other shoot-em-up titles: Giga Wing, Psyvariar, and Ikaruga.
Some bosses are so dense with bullets that the game actually starts slowing down. It even seems to me that the game is balanced around this. You get more time to figure out how to navigate a field packed with bullets and your ship moves slower, which lets you nudge around safely.
It was originally released in 2003 by Kenta Cho (aka ABA Games), who has made a name for himself making shmups and quirky minigames. A few years ago, he updated it, and more recently, someone ported it to Switch. He also created a markup language called BulletML for describing bullet barrages, which has appeared in some of his other games as well as in games by others.
Getting the game
rRootage costs nothing. The official page offers Windows downloads. Some Linux distributions offer a package, and if yours doesn't, you can get the Flatpak.
(It's also free software released with the 2-clause BSD license, so you're free to mess around with its 2003-era C++ codebase, which features an obsolete version of SDL. Good luck building it from source.)
Bonus video
This is me somehow making it through a relentlessly fast bullet pattern on pure instinct.
Seriously, truly incredible games from this developer. Bringing my kids into the fold now!