@OptionSelect thank you for your feedback, I am glad that you liked the game.
Yes, sometime the UFOs are a bit nasty but I guess the game wouldn't be too fun if all of them were easy to destroy. It has only 10 UFOs, 2 of each kind. The speeding ones and the colour-changing are usually the ones hard to destroy. When playing remember that to add a three-dimensional feeling, when shooting it takes a bit of time to reach the target so you will have to anticipate them. The running UFOs often come back in the screen once passed, so be ready to catch them when they come back to mock you.
I am getting general positive feedback from the game here and elsewhere. I might decide to expand more the game from single level with only 10 UFOs to a complete game with few levels to play.
Everyone is welcome to keep chatting about the game, to me it is more satisfying rather than win a prize for a Jam :-)
Thank you again for take time in playing the game and give feedback!