Thank you for the feedback! We're so disappointed that we weren't able to fully deliver in the end, but glad to hear the positive comments you can still offer us.
Believe it or not, the small screen in the bottom right corner is not the bug. The game is meant to have two different viewports, the smaller first-person screen in the corner that's meant to represent your camera, and the fullscreen third-person screen that's meant to show your submarine in the game world. For reasons unknown to us, the main viewport is not rendering any game objects in the browser. We suspect it may be a performance issue with culling.
As for the LMB, the "camera" was one of the last mechanics we implemented and we unfortunately ran out of time to add any feedback on activation, or connecting it to the checklist on screen. However, if you press 'J' (which we also forgot to mention in the controls section), your "journal" will open up, which will show the pictures you've taken of the different kinds of fish. Once you've collected all four pictures, a victory screen should appear, and as far as we can tell, these features are still working in the browser.
This was our second game the two of us have ever made and we've learned a lot. We apologize for the technical issues the game has and any inconveniences they may have caused, but we're happy to hear that people were interested in playing our game. Thank you once again for the comments :)