This game need a lot of work to be considered really decent. Hopefully you can earn enough to get the full version and correct the issues in this game.
The graphics are simple which is nice. This sadly seems to be the only real positive I can think of for the game. The rest seems to be a bit of a train wreck.
First, the ship itself. When it moves, I feel like music is playing, yet when I stop the ship, the sound halts. Would be nice if it sounded more like an engine (even a very silent ambient sound work here since rockets usually don't make much sound in space as far as I know). The firing is not too bad, thankful that I can spam the shooting without having to wait for it to recharge for a set period of time.
Second, the comet is a really big issue for me. It almost always hits and you have little to no time to move out of its way before it hits you. A warning would be nice but for the comets to always have pixel perfect aim at the ship seems a bit unfair. At least try to rewrite the programming a bit so the direction of the comets is random instead of targeting the ship.
Third, the pulsars seem to glow blow and take off a good chunk of your health it seems. I was just flying, it grabbed me and a comet hit and knocked me down from 100 HP to 10 HP then a comet hit me directly again. Not too bad though since the tug is not too strong.
Fourth, the black hole is what made me quit the game. It's near the start of that level and you are given little to no time to move (you need to go up and up and then right once at the top of the screen). Right as soon as the level starts, it sucks you in and instantly destroys you and takes a life away. If you plan to have something that strong in the level, give it less of an area. That ways if you do happen to get close to it, the death is more justified rather than having it occupy almost all of the screen with its powerful tug.
Lastly, if you can do it or get a friend who has Construct 2 to do it, add checkpoints. Getting destroyed my the black hole constantly was harsh enough and then to see you have to restart the game from the very start can really kill any motivation a player has to play the game. I can understand if this was a short 3-5 level game and not seeing much need for checkpoints but given how long this game is, having a few would be really helpful.
Overall, it's below standard for a game in Construct 2. I really hope you can fix all the issues I present to you in my review. Best of luck on future pieces, I hope you improve with time.