Actually that level really is pretty easy to beat if you are patient and don't get flustered. If you listen/watch carefully, the machine guns fire in a very very predictable pattern with a noticable pause between them. Just move from shield to shield during those pauses. There's enough time between them to get to the base of the nests without even getting hit.
That level is playable without cheating. You just have to pay attention to all the shields scattered in the water. I also got a patch from the good medic man in the middle of the way behind one of those shields.
The one game I never hesitated to cheat in was Clive Barker's Undying. If anyone has finished that thing without cheating, GOOD for him/her but I had another reason, I was SCARED. One night when I was killed by a group of skeletons I just said to myself 'Thou shan't touch this game ever again without a cheat code!'