I really like frame locked, often using sprite system, type games. Atari VCS comes to mind, as do many other systems that have sprites and some means to sync with the display.

But the feel of those is crisp, sharp edged, fast, sometimes too perfect if you can maybe guess what I mean.

Bitmap games are different! The drawing, masking, and every other thing happens on the CPU. It feels a bit wild, and the feel varies. Number of enemies, missiles, etc... do often change the speed a little. And that's nice, kind of wild! The game feels alive in a way. Not living but not stale either.

The author packed a lot of shooter into a 256 x (whatever) screen. And the art is really good! Takes a bit of talent to make multiple baddies stand out amidst quite a bit of background detail.

And the sounds! Little bits of this and that packed into the game loops. That's a feel I like too. Often sounds are just a click or beep. But sometimes there is a little more, and this game does that.

Great work. Just my kind of game.

Fun bit: the explosions and possibly other sounds were just us pushing graphics bytes to the audio port (a 1-bit piece of metal which you had to flip in software to make it vibrate) as we rendered them. A poor man's source of noise.

On my 2600 game Ooze! I would drop item Y values into the audio registers as a poor man's way of making some cool sounds of enemy advancing.

Same for the player missile. As it travels, some variation of its Y value becomes the sound.

Tossing bytes at ports does insure the user associates the noise with the right on screen action.

Anyhow, great art! You did a fine job making things stand out and that is not easy.

There's always Elite, a whole space sim game in 1984