This game is easy even on hard, and it gets easier the farther you get in the game as your character acquires more health and stronger weapons. You can run and gun haphazardly at all but the earliest parts of the game.
I watched my younger brother play on medium. It seemed painfully easy.
This game is pitifully easy on hard. Unless you meander around in the open during a gunfight you really shouldn't ever die. Save for blood dragon fights, but by the time you are required to fight them you should be pretty well equipped.
http://www.backloggery.com/chosen_one_41 Rarity is best pony
There's no denying that this is an easy game, BUT it's easy in a fun way. You're suppose to feel like a true 1980s american badass while playing as Rex. Badasses run through entire hoards of enemies, sponging bullets while decimating everything in their way
If you want kind of a challenge, you can try playing the entire game 100% stealthily, but even then it's quite easy