Itch.io page: Hyper Ultra Astronautics

Hyper Ultra Astronautics is at its core a simple space arena shoot'em up  with solo, competitive and co-op game modes and wide selection of weapons. The less usual features are semi-realistic thruster based movement, teleport technology based mechanics and support for up to 16 players on a single PC (Windows or Linux).

Gameplay trailer (slightly out of date):

The game has been in development for a very long time and it is now nearly ready, but I'm still looking for feedback on the beta versions. All feedback will be appreciated!