Wow, dude, this thing is incredibly good. It feels like a real honest to goodness game, not a jam game. I expect to be reading about the Steam release on IGN in six months. I was playing this for an hour and having a legitimately great time. The mechanics are just so solid. I love this sort of twist that you've put on FTL-esque mechanics while, at the same time, being nothing like FTL mechanically. My girlfriend walked in while I was playing and asked if this was the sequel to FTL, so you should feel some pride, there.
That said, I think your tutorial needs work. This isn't really a complex game at the end of the day (or, at least, mechanics are introduced so incrementally that it's totally palatable). But as I flipped through your tutorial I was like oh god oh god oh god. One of the issues is that it's hard, visually, to differentiate between tututorial text and normal UI text. So that would be my first change since that's pretty easy. Ultimately, though, I think you could easily have a playable tutorial. Like, you just play using the base ship against a stock level 1 enemy and explain the buttons and mechanics with pop up text as that happens. Then the player unlocks a block as a reward and you walk them through adding it to their ship, ba da boom.
Some quality of life things I would like:
I wish I could replace blocks with other blocks instead of removing the module, (trying to remember what module I had there), removing the block, placing the new block, replacing the module. On top of that, it's hard to parse where you should be upgrading. I wish when I hovered over blocks on the ship, the left would show information on the module, and then also information on the block (weight, HP). I got a bunch of new blocks and I would say "Okay, now what should I remove to add you..." And that question is kind of hard to answer, visually, especially with so many blocks looking so similar. And the game is 80% incremental upgrades, so the user goes through this process a lot!
I wish I could get lives back. I lost both of my lives in world 1 when I was trying to learn the mechanics. Ultimately, I got really far (world 5 or 6 maybe? I lost track), but the lack of lives was a bummer. I think it might even be fair if the end world bosses always offered you one life as a loot option. So it's recoverable a bit. I would settle for a chance at a life, even.
The treasures seemed abnormally bad. I'm not sure if there was a bug and you can only get world 1 treasures, but I would be in world 4 getting sand and 6 gold. Maybe that's intended? But it didn't feel good.
I'm not sure what the solution to this is.. But the AI ships outclass your ship pretty quickly. And I see why that is, I think. I wasn't particularly struggling against their better ships using my human brain, but it was kind of a bummer to see them with 60 missiles and shields when I had pea shooters. Even if it turns out that's pretty balanced. Shrug, just an observation.
Overall, definitely my game of the jam so far. Extremely well done.