The game has controller support but I gave up playing it with the gamepad after I met my first enemies. I think it’s impossible to win this game by playing it with a controller. You constantly have to aim very precisely and I could do it only with my mouse. (Maybe some people want a real “challenge”. Plug in your controller and play.) The game is quite difficult, even though you have unlimited respawns and ammo and I died quite a lot before I understood what I had to do in specific moments. But after your first playthrough you can try to play on a harder difficulty level, in case the game was too easy for you.
I really like the art style of the game and it made a big accent to it. Wherever you go you will meet new unique drawings, pieces of landscape and other stuff. While playing I even died sometimes, because I was busy looking at that lovely world (and looking out for easter eggs. By the way, I think the most unnoticeable of them were references to Solid Snake and Black Mesa). Each piece of the story telling is made of different pictures with speech bubbles. For some unknown reason the game does not offer voice dialogues, so we have to read the whole story bubble by bubble, like a comic book. At least the music is pleasant and doesn’t distract you from reading and understanding the plot. But the story as a whole is very captivating and making you want more of it.
Sometimes you can find secrets (a round target) by doing things that you could miss sometimes, e.g. shooting the ghosts flying out of dead grunts or killing a duck, which is flying by while you are under attack. But I don’t know if you need these secrets for something other than the achievement.