Using airship to travel between planets , is easier than by foots or using submarine ^^.
Yes, I procrastinated too much this week, didn't have the time to make a real level, this will be the next step.
Oops, launching again the game to take screenshot and add a banner on Itch.io, I just noticed that first wave of enemies is not triggered in the released version, I changed too much parameters at the time of the release :(... I will try to update it on official tic80 site, until the end of the vote and change again on itch.io after the end of the vote.