Back in August, RunGunJumpGun arrived on Steam for Windows and Mac. The game is an incredibly difficult platformer with a "gravity-defying weapon," which you use to both shoot and fly. You have to fire the weapon downwards to propel upwards, while occasionally firing the weapon forward to blast through walls and other obstructions.
User reviews for the game on Steam average to 'Mostly Positive,' and it has an 82/100 rating on Metacritic. Now the developers have released RunGunJumpGun on the Play Store for the low price $2.99 with no in-app purchases. The mobile port is exactly like the desktop version, with the two buttons mapped to each side of the screen (left tap goes up, right tap shoots the gun).
Trying to juggle between flying upwards and shooting is extremely difficult (at least for me), and collecting all the 'Atomiks' is an optional objective if you manage to not throw your phone at the wall. The game itself is very well-designed through, and I enjoy the soundtrack the developers call 'Hyperkinetic.' I didn't notice any performance problems on any of my devices, if you are concerned about that.
With 120 (not automatically generated) levels, I would say the game is well worth the $2.99 price tag. If you would rather play on PC, the Steam version is 60% off at the moment ($3.19).