Quite simple. Reminds me of asteroids, except you try to hit some of the rocks instead of avoiding and destroying them all. I feel like this needs some more tweaking to be addictive.

It would be great to make targets moving, to complexify their discovery :) Nice idea, indeed.

Needs a lot more depth, yet this somehow seems like a good start for a good game if the sonar idea was expanded.

I think it could go somewhere really good with a couple other gameplay elements.

Excellent concept, but got old quickly. I didn't like the fact that when you are moving, pings get mis-timed.

Obviously my main browser is too old (snicker) and it doesn't work in FF for me. Ain't HTML5 grand?

Simple, innovative concept. Not much actual gameplay though. Anyhow, nice job. Get well soon.

Great potential. Needs a score and a little more motivation aspect to hook the player to keep playing.

I see a lot of potential here. I really like the sonar mechanism. Personally, I don't think having a lot of action (shooting, etc.) would benefit the game. The ambient, meditative hunting feeling works for the game.

It would help the perception of the sonar a lot if there were an initial "ping" immediately when you hit the key. Then the other pings would sound more like echoes (and it would be easier to estimate the delay).

I like the sound the and visual indicator of sonar. I also want more to do and think about doing. Oddly, on my setup, I could not get it to play in Chrome or Internet Explorer. On Chrome it said something like "overwrite sys.screen.draw". So I played in Firefox.

Good basis for creating a real cool game!

The tension in the moment just before hitting a supposed capsule make that 'Bing!' really hit the spot!
Maybe it would play even better if the momentum of the ship was less awkward & the planets would be slowly moving.

I agree with other commenters that this needs more depth. Also, the ship turns too fast and you can't see the sonar marker when you are right next to a circle (planet?), which is annoying when there are two circles close together. Good start though.

Cool. But sometimes planets killed me at beginning of the level.