Galmedes is a simple mid-school vert shooter with lots of colorful enemies and a level of difficulty that puts it into the GOTD Rage-Inducing Games Hall of Fame.
Of course, despite its difficulty, it's a very fun game or it wouldn't ever be a GOTD.
There are two buttons to use along with the joystick. The two buttons are shoot and change weapon. You start with a simple gun that can be powered-up into three other types of weapons: laser, wide and torrid. The torrid shoots out of your ship 3 different directions including behind you at an angle. Additionally, each diff weapon can be powered-up/supercharged with additional power-ups of the same kind. So, for example, if you are using the wide weapon and the appropriate power-up for wide comes along, it'll become a stronger/more powerful wide shot (and the same goes for the other weapons).
You use the 2nd button to choose among the weapons you have available. When you start, you only have the normal shot and none of the other three. However, as you collect the power-ups for the other three, they light up in the little boxes in the lower left corner of the screen to show they are available. Then if you hit the 2nd button, you shuttle between each of them you currently have available.
By the way, the power-ups are all color-coded - and they match the color in the box that indicates your weapons. (blue-laser, yellow-wide, red-torrid).
If you die, the current weapon you are using gets blown up and disappears. You have to use another weapon until you get the power-up for that one again.
There are bosses and changes of background, but essentially, this is just an early 90s shooter on 'roids with a little bit of Galaga flavor added in.
There's a simple reason the game is hard, evil aliens attack your ass relentlessly in all sorts of configurations. They don't ever stop coming, they happily crap bomb-turds on your head and they keep you constantly on the move. Good luck getting very far the first couple of times you play.