3 days 23 hours 19 minutes (yeah yeah, pretty slow, but at least I got all the upgrades plus an extra skill point)
It's a nice game. There is a more than good selection of guns, even if I only tried 3, including the one you start with. The enemy difficulty curve is nice in the beginning, too slow after that. Players need to be forced to buy new guns and get gun related upgrades. The ending is nicely foreshadowed, the larger enemies are a bit stiff and lifeless, but all are nicely designed and well drawn. The game is a tad limited in its scope, somehow I can't help thinking some more game elements may have helped. Some sort of slowing walls or traps perhaps? Some preparations that you must spend valuable upgrade time on? I don't know. Anyway, 4 stars.
And no guys, there doesn't seem to be another ending.