I only occasionally pick up ammo for a gun I don't have; in order to make things easy the game limits your ammo finds to whatever gun you have equipped
I'm surprised it took that long for someone to post that. Really the ONLY two weapons you need are the plasma cutter and the pulse rifle. Everything else is just too fucking slow/weak/oh god I've blown my own face off to matter. Plasma cutter works for pretty much every single situation except OH FUCK THERES 30,000 ENEMIES where it's fun to hit the alt fire on the pulse rifle and cry in a corner.
Also after getting through the horrible crashy bridge section, I've now just arrived
with the marker on the colony. But it crashed again. Gonna try and finish it tonight. The SCARE FACTORY of the game has pretty much gone away with fully upgraded suit, guns, 5 big medikits and a million bullets, and I'm only really dying to mechanical devices by accident now. The last few chapters have played more like a romp than the survival horror glory of the earlier chapters.

(I blame the shop for this, like most people). I think the game is too easy on normal personally, but I don't know if I would want to replay it again on hard as it's so linear. Still, even if it's formulaic, unoriginal and unscary it's still creepy as fuck. Particularly
all the people lined up with their heads masked and bullet holes in their heads in the 'temple' by the station.I'm totally used to the controls now, but I still think this would be better in first person (if they figured out how to get the health meter on screen without a GUI still).
Also, regarding the 'invincible' enemy
you'd think that having to blow it's limbs off repeatedly, box it in rooms, starve it off air, poison it, cryo-freeze it and eventually incinerate it to kill it it'd be more powerful than the weakest enemies in the game. I liked the idea and it did tend to make me panic at first..but it's so slow and weak it's not that scary.