I don't believe I ever lost durability on forts. Once I got a fort, I would just blast enemies with the second gun, until they gained on me. Then, up into the fort to sleep. Escaped in 66 game hours.
Meh. Starts off with a steep learning curve, then becomes trivial about midway through game, after learning which upgrades own everything.
The final level was hard, until you max everything out (easier than it sounds, at that point), and then it is a cakewalk.
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