Go to the Store page on Steam and click the button to opt in to the test, this will allow you to install the demo (note, apparently limited demo downloads so get in quick if you want to try it). There's good tutorial videos and the gameplay is challenging. Publisher asked developer to delay the demo as it was 'too realistic', but they seem to have pushed back, because the demo is not easy.
If you like high-stakes mental geometry this is a lot of fun. Here's a few screens. My first go, I did terribly and Jerry sank two ships after sneaking past me. Very atmospheric.
