So you routinely get these inadvertently hilarious, '75% chance to hit', player model gun geometry is literally intersecting with the enemy's head, point-blank misses. The other aspect of the last-second changes they made were to drastically decrease the applied hit percentages (so, not the guesstimate it shows you on the screen, but how they are seeded into the level as it initially loads). You can find interviews online where the developers explain the hell that was the final couple weeks of development. You can't possibly kill everything, but the mandatory timers mean you can't bull rush things either. It's a very poorly balanced game: the story is that at the eleventh hour, they decided that it was too easy, but they didn't have enough time to re-balance the right way so for the back third of the game, it throws a positively absurd number of enemies at the player, to the point where every time the screen scrolls you get these 'you have got to be kidding me' kinds of situations.
