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When I quicksave, immediately after I've confirmed the quicksaving by pressing Y and I'm taken back to the game, the player commits an action such as jumping or shooting, which is kind of annoying, because it wastes ammo.

It kind of looks like the game repeats the previous action the player had made before quicksaving. E.g. if I had jumped before pressing F6, then after quicksaving the player would immediately jump again. That's seems to be the tendency, but after just having tested with SW, the player instead shot his weapon, even if my previous action had been jumping.

I've tested with Duke, Blood and SW, and all of the games exhibit similar behaviour.

Something similar happened to me just now, too. I died and then quickloaded and Duke fired his shotgun immediately. I am thinking maybe I had clicked before quickloading and it carried through.