Sci Fi four Kids selected from earth for testing to allow earth to join

[Travis]

This book starts out with a kid living with his mom. Dad was science fiction writer that went missing some time ago. He is selected as the random fourth choice. Kids go to space where they earn experience points to level up. A few other worlds have kids or youths selected for the same.
First part of space flight, boy is on the bridge learning to pilot and blows up attacking vessel but violates laws to do so.
Kid meets cat type girl. Ends up finding planet with prison on it. Finds dad there and frees him. Cat girl hacks system and gives him max level during the break in.

[Ayshe]

Is it Randoms?

[Michele]

Travis, when did you read this and/or do you know when it was written? Was this YA or adult?