Star Drifter (Steam key).

http://store.steampowered.com/app/485330/
Features:
Level up your space pilot. Earn points by destroying enemies and surviving. Spend your points at the shop, upgrade your ship and equip a variety of defence and weapon systems.
A massive amount of randomly generated enemies, power ups, secret weapons and huge bosses.
Protect your ship! Exit your ship and attack the aliens while your shields are regenerating.
An awesome authentic chip sound track.
Disclaimer:
Star Drifter is a full screen action space shooter. You play with your keyboard. We have developed the game to feel like an old school arcade, hard, very hard, super punishing space shooter. The game is not easy and you will die a lot. Please take caution, if you´re in the mood for something that will hold your hand or let you win, you´re in the wrong place. Star Drifter is ideal for casual gamers that enjoy a real challenge. Prepare to be destroyed over and over again, lose your score and rage at the computer.
Thank you and good luck!
Dan and Martin.