It was really nice, good choice of colors and I appreciate that there were so many versions of the gems even if they are interchangeable. Solid gameplay and visuals, though I would have liked the Kaiju to actually be a part of the game more than just shown at the end haha. I didn't get the impression I was going off to kill a giant space monster, maybe just a single drawing of the monster attached to the asteroid attacking your spaceship, then have a small crashed spaceship next to the player starting position and that would have been enough storytelling-wise to give the game context.
Personally I like to do things in a similar way to old games, like in Super Mario where all the context you need to know is that the princess was kidnapped and taken to a castle. You can see this used in a lot of older games. I used this principle in the game I submitted to this Jam (DragonSlide), just a short cutscene and that should be all the context you need. Imagine if Super Mario just started off with the first level with no story intro, if there were no princess Peach at the end of the game.. Without it the game wouldn't feel as complete, or rewarding to finish. Or how strange it would feel if we only found out that the reason Mario went on a murderous rampage assaulting multiple castles was at the end of the game when we rescue the princess.
TL:DR
Don't leave out an introduction to the game, it adds a lot!