lots of updates

I would call this a playable game at this point! All the major pieces are in place.

What remains is lots of polish - there are still barely any particle effects, unforgivable 🙂

Major changes:

• The core gameplay loop is now complete, with a title screen, GAME OVER screen and restart.
• The title screen gives you a sort of guide to what's in the game, but without giving EVERYTHING away. This is a tribute to 1980s arcades.
• There's a boss!
• You can score and HI SCORE.
• The SUPERBEAM weapon has a limit now! Thanks to Fernando Lores for the idea.

Smaller changes:

• Some enemies take 2 hits. Some take many more.
• Illusion of depth: there are sparkles on the sea far below and dust flying fast above you.
• Invincibility phase (glowing yellow) after you respawn.
• Cute red stars to show how many 1UPs left.

Let me know what you think!