Hyperspace Dogfights is a really intense and rather good jet-combat game available on Linux, it just had a juicy content update today.
The "Realspace" update adds in quite a lot including: 6 new active item, 11 new weapons and 30 new passive items, gamepad support, item tooltips, the ability to change the color of your jet's reticle and a few more other quality of life updates to improve the game.

Direct Link
Some of the other features you will find:
- Impactful, tense 2D air combat in a weird sci-fi universe
- Colorful pixel art, powered by the Pico8 16 color palette
- Strong focus on building your jet into something unique with stackable items that interact with each other
- Over 100 different passive items ranging from simple bonuses to complete jet behavior modifiers
- Over 50 sci-fi jet weapons, including lasers, explosives, and aerial melee options
- Over 40 active items used for offense, defense, or utility
- 7 zones with distinct enemies to discover and destroy
- 10 bosses to try your luck against
After trying it out once again today with the new gamepad support, I got my trusty Steam Controller and had a blast. The controls do need some adjusting, but once you get them to your liking it's not bad. The menu definitely needs improvements for a gamepad and they ideally need to support showing the more human-readable names of buttons like ABXY and so on. Hopefully this will all be improved in another update.
Sadly, it's still a pretty poor experience if you have more than one monitor. It messes up my resolution, turns my second monitor off and it just becomes a pain. It's annoying, because the actual game is fantastic, but whatever they use for windowing is terrible. Still, I'm likely still a minority as most people generally only have one monitor.
Check it out on Steam. It's also on itch.io but I'm not sure how up to date the build is.