Just submitted my first alakajam entry a day ago.

It was fun, but stressful at the same time. I basically wrote the game's framework in vanilla javascript during development (except for the audio which was handled with Howler.js). I really tried to follow the OOP pattern, but ended up with a bloated file and a messy code. Here's the spaghetti source code for anyone who's interested to tinker it. Also, the game is not balanced. The first wave is difficult, but past that everything is basically a cake walk. I'll make some updates after the event.

Still, this was an amazing experience. I'm looking forward for the next alakajams.
Good luck everyone!