Some arcade games

1. xgalaga

Clone of the old game Galaga. Ship moves by moving the mouse; autofire by holding mouse button. https://sourceforge.net/projects/xgalaga/

2. koules

A game where you are a marble and have to bounce other marbles into traps/edge of the screen to finish the level. There are powerups that increase your mass so you can hit other marbles farther and speed which makes you move faster. Watch out for spikes and black holes. http://www.ucw.cz/~hubicka/koules/English/

3. Maelstrom

Kind of like asteroids. Shoot asteroids to break them into smaller asteroids. However, this game has powerups to collect and UFOs to avoid. When you see another ship like yours flying around, fly over to it and you get an extra life. Don't shoot the stranded ship or it will just disappear. https://www.libsdl.org/projects/Maelstrom/

4. Kobo Deluxe

An arcade game where the goal is to shoot the yellow or purple circles to make the maze disappear. The blue circles can be shot at to get rid of some maze walls. Shoot everything to increase your score to get more ships. The asteroids in this game can't be destroyed. http://olofson.net/kobodl/index.html

5. Heroes-Tron

This is a game like Tron or Nibbles and has several power-ups. To get to the next level in quest mode, collect enough purple trail +1 power-ups (marked with a capital L and a yellow arrow pointing to the power-up) to have the end of level power-up appear. Normally, it appears when any player is at length 10. Purple power-ups have an effect on you, white power-ups affect all the other players. https://savannah.nongnu.org/projects/heroes/

6. Geki 2

Geki 2 is a shoot-em-up game that has 6 levels each with a unique boss, and after the sixth level, I think it loops back to level 1. There are two power-ups in this game, S and L. S switches your shot type to multiple shots and L changes it to laser; both increase the strength of your attacks if your shot type is already the same as the power-up's shot type. The power-ups are inside the barrels that show up every now and then. I have uploaded the code at https://github.com/Quipyowert2/geki2/ You can also view the original Geki2 homepage on Wayback Machine. I got the code from http://triring.net/ps2linux/games/kxl/kxlgames.html.

7. PowerManga

Another shmup game each gem you collect gives you choices of different ship upgrades rather than powerups. The pink gem causes an explosion. Use arrow keys to move and Ctrl key to choose the currently selected upgrade in the panel on the right.

8. CriticalMass aka critter

Another shmup kind of like PowerManga; however this one's controlled with the mouse. Click to shoot.
http://criticalmass.sourceforge.net/critter.php