[RANT ON}
The more I play this, the more it becomes an exercise in sheer frustration - largely due to the lack of checkpoints/save ability and some of the stupid jumping requirements.
Level 5 - finally worked out how to progress onto the bridge and cleared the middle room (where you get the weapon upgrade). Then went to try and jump the big gap over the broken twisted bridge and fell... Guess what, right back to the beginning of the level. Done that three times now and I can't see an alternative path. I want to play Doom not some masochistic variation on Super Mario or Silly Putty. As it stands, within a hairs breadth of getting uninstalled and reclaiming 50Gb of HD space for something that's actually enjoyable and not designed to raise the blood pressure or induce rage-quit.
[/RANT OFF}