It's done!
Well, sort of.
I'm not going to lie: the game is finished, but I don't feel like it's complete.
However, since I've worked on quite bad conditions (damn you, holidays!), on a language I didn't know, and with my computer randomly dying a few times, I'm quite happy I've managed to do something at all.
Perhaps I'll return to this game someday, although for now I want to focus on my other game, as I really want to finish it this year.
While I'm not very satisfied with this one, it gave to me motivation to progam again, and that's something I realy value. Also, learning how to use Java was very fun, even if I have some complains about it.
You can download the game here or see the source code here. The game has a small guide but the gameplay is really basic: move with WASD, press CTRL to fire lasers, press ENTER to go in and out of your ship, when you're out of your ship you can press 2 to put extractors on planets, extract minerals and go to the shop to sell them or buy new components for your ship, buy the spacial interpreter to open the spacegate, find the spacegate to win.
Also, watch out for your o2 and fuel meters. You can buy more tanks on the shop. Press T to use them.