I've published a free Demo of my game Dogstar here: https://dogstar.itch.io/dogstar
Dogstar is a retro-arcade gravity and vertical shooter for 1 or 2 players with you as the intrepid hero from Canis Major (Dogstar), on a Journey from Jupiter to Venus to cleanse the system of the alien scum and rescue your comrades. Equipped with an all-powerful smart-weapon that boosts rewards depending on what you shoot it at, challenging stages that are galaga-esque, enemies you can turn into weapons of mass destruction, and level progression with gradually scaling enemy AI, and plenty more.
The Demo contains three levels: Mars - single player, Jupiter-2 Co-Op multiplayer, and the single player Jupiter bonus stage.
I hope you have some fun with it :)