I'm not a big fan of tower defense as a genre over all and doing it blind doesn't really do it any favours. A neat idea though but it is indeed kinda lacking on difficulty scaling and probably different levels. You only really need few turrets and the game seems to go on forever with those.
Nice dual take on the theme. Enemy waves and sonar waves o reveal stuff. Though technically there wasn't enemy waves but just a single endless wave.
Looks good with a nice cohesive style. Too bad you weren't able to take full advantage of eveything you had created. Looking at the screenshots, I guess there are multiple levels. Random maybe? Shame really that such a minor thing as adding level changes and increasing enemy spawns was keeping this from being a more full enjoyable game.
I guess the game isn't meant to be played for as long as I've had it running now since the music stopped too without looping. The sound effect gets also rather irritating with so much repetition.
Anyways, good job! 👍 Hope you at least learned something this jam, maybe to manage your time better and scope the game more appropriately.