Alex Detail's Revolution, a young adult Choose Your Destiny novel by Darren Campo, is free as a paperback from Amazon. Regular shipping rules, though, so if you don't have Prime or another free delivery plan from Amazon, you'll need to get up to $25 for free delivery. The Kindle edition, if you'd prefer it, is also marked down to $2.99 for now. This is a limited time (and probably limited copy) promotion, but there doesn't seem to be a limit to how many you can order from one account (I've ordered one for me and sent another to nieces for Xmas).
Book Description
17 year old Alex Detail has been kidnapped and sent off to fight in a hopeless war against The Harvesters, an alien force that is trying to extinguish Earth's Sun.
Unfortunately for Alex's kidnappers (and the world) he has lost the mega IQ that allowed him to win the last war with The Harvesters ten years ago when he was just 7 years old.
But now the House of Nations is out of options. The end of life is imminent.
Alex must save his ship, fight his evil clone and survive the war long enough to make it to Pluto, where, underneath the planets frozen surface lies the only force in the solar system that can stop The Harvesters.