I got PWONG PWNER on Hard, Extreme and Insane easily. Just gradually buy every single upgrade, and it will be easy. In Insane mode, since the level is short but (if) you should have every single upgrade so it will be quite easy. When it comes to the massive ball fire in a diagonal line, I always have like 30 ammo and a large paddle so fire your ammo and watch the opponent get pwned by balls and you should get loads of score!
With the 'Travel' achievement, does it mean in total so that you have to build up to it or in one single go? If you know the answer, please shout into my account ASAP! Thanks!
 "Ragdoll Cannon 2"){kind=icon}
 "GeoSketch"){kind=icon}
 "Epic Battle Fantasy 2"){kind=icon}
 "Ragdoll Avalanche 2"){kind=icon}
 "Pwong 2"){kind=icon}
 "Scratch Out Terrorism"){kind=icon}
 "Robot Dinosaurs That Shoot Beams When They Roar"){kind=icon}
 "AirDrop"){kind=icon}