I gave up at level 4 boss fight. In a locked circular room with a boss bot that seems indestructible and fires at all directions at once and does not miss, with too many other lesser bots respawning continuously draining all your secondary weapons and guns. No way I could defeat this boss in order to get to the reactor section unless I play at rookie level and even that might be too tough. You cannot save during a boss battle so if you die you start all over again.
